Abstract:
An ATX compatible power supply unit having at least one DC power outlet and at least one DC power cable, the DC power outlet configured to support nominal contact resistances of less than 2.5 milliohms per contact or the DC power cable configured to support series resistances of less than 4 milliohms per linear foot of individual conductor is disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is related to Patent Application Ser. No. 12/714,366filed Feb. 26, 2010 entitled, “AC Interconnect Scheme for PSU,” by Don Lieberman et al., and Patent Application Ser. No. 12/714,415 filed Feb. 26, 2010 entitled, “PCB Interconnect Scheme for PSU,” by Don Lieberman et al. 
     TECHNICAL FIELD 
     The present invention is directed to power supply units for computers, and more specifically to aspects relating to the efficiency of power supply units for computers. 
     BACKGROUND 
     Personal computers require power supplies commonly referred to as power supply units (PSU) to generate multiple voltages needed for proper operation. The main boards (motherboards) and peripherals of personal computers generally require multiple voltages for operation, including 12 Volts, 5 Volts and 3.3 Volts. Power requirements of the central processing units (CPU) on the motherboards and the video controller integrated circuit (IC) on the peripheral graphics cards have increased dramatically. As a result, the overall power requirements of PSUs for personal computers have increased. High end gaming computers use power supply units that source 1000 or 1200 watts, for example. Most PSUs are configured with industry standard AC input power connectors as described by IEC (International Electrotechnical Commission) specification 60320. Thus, most PSUs for personal computers use IEC connector versions C13 for power cord and C14 power inlets to supply AC power to the computer. However, as alternating current (AC) input currents increase dramatically, IEC 60320 versions C13 and C14 prove less than ideal. The voltage drops across the complete interconnect path including the input AC line cord and power inlet connector from the line source to the neutral return can approach 1 volt at 11.5 amps. This results in a power loss of approximately 11.5 watts which is roughly equivalent to a 0.7% penalty in the overall efficiency ratings of a 1200 watt, 87% efficient PSU. Such losses largely originate from two sources: 1.) The voltage drops in the IEC320 power cord are a result of the use of cable with insufficient diameter (the AWG rating and resistance is too high); 2.) The voltage drops in the IEC320 inlet originate from high contact resistance between the inlet and the mating end of the power cord. 
     Further, current PSUs use an array of modular cables for direct current (DC) output from the PSU. Such modular cables incorporate sub-optimal connectors having too high contact resistance and wire of too high series resistance and are not optimal for supplying sufficient current while minimizing power losses to key chips on motherboards, daughter cards such as video controller cards, and peripheral devices associated with the computer, for example. 
     A further problem is the way in which such sub-optimal connectors are wired to the DC output electronics of the PSU. Presently, bundles of wires are used to connect the PSU circuit board containing the DC output regulators to another circuit board containing an array of connectors required when implementing modular cables. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a high-level schematic that illustrates the use of IEC 60309 as an AC interconnect for a PSU, according to certain embodiments. 
         FIG. 2  illustrates some international plug types, according to certain embodiments. 
         FIG. 3A  and  FIG. 3B  illustrate the use of a terminal block in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 4  illustrates the use of a circular connector in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 5  illustrates the use of a rectangular connector in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 6  illustrates the use of a direct connection in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 7  illustrates the use of a direct connection in an AC interconnect scheme in conjunction with a connector to join a portion of the AC cable that includes the AC plug to the rest of the AC cable connected to the printed circuit board for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIGS. 8A-C  illustrate the use of multiple connectors associated with AC power cables on a PSU, according to certain embodiments. 
         FIG. 9  illustrates the use of a terminal block in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 10  illustrates the use of a circular connector in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 11  illustrates the use of a rectangular connector in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 12  illustrates the use of wave crimp connectors in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 13  illustrates the use of bus bars and clamps in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 14  illustrates the use of an extended horizontal printed circuit board (PCB) in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 15  illustrates the use of an extended horizontal printed circuit board (PCB) in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations, according to certain embodiments. 
         FIG. 16  illustrates the use of a pin interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 17  illustrates the use of an array of high current connectors to interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 18  illustrates the use of multiple arrays of connector fingers and multiple high pin count connectors as an interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 19  illustrates the use of multiple wide fingers and corresponding milled slits as an interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 20  illustrates the use of an array of right angle metal brackets to interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 21  illustrates the use of an array of straight metal brackets and corresponding milled slits to interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 22  illustrates the use of braided flat cables and corresponding milled slits interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU, according to certain embodiments. 
         FIG. 23  illustrates the use of a plurality of connector arrays mounted directly on a horizontal PCB, the plurality of connector arrays for use as DC modular cable outlets, according to certain embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     According to certain embodiments, the output connectors of the PSUs as described herein are not the standard output connectors as specified in the Advanced Technology Extended (ATX) specification but are compatible with the output connector standards specified in ATX specification. 
     The standard specification for the contact resistance for a mated pair of IEC 320 contacts is about 10 milliohms. By reducing both the cable resistance and the contact resistance, the power loss created by an existing AC interconnect scheme can be reduced, according to certain embodiments. This would reduce the power wasted in the cable/inlet combination, thereby increasing the overall efficiency of the system. Further, the temperature of the power cable would be reduced. 
     According to certain embodiments, a variety of AC interconnect schemes can replace an IEC 60320 C13 power cord inserted in an IEC 60320 C14 inlet for AC interconnect for use with high current power supply units that are compatible with computers such as personal computers and workstations. Features of suitable replacement AC interconnect schemes include the ability to support comparatively low gauge wire that offers low series resistance coupled with connectors that offer low contact resistance at connector mating interfaces, according to certain embodiments. Further, such replacement interconnect schemes permit the use of a variety of AC plugs depending on the country (and its electrical codes) in which the PSU is used so that power can be sourced in any country in the world. According to some embodiments, the variety of AC interconnect schemes do not replace an IEC 60320 C13 power cord inserted in an IEC 60320 C14 inlet but rather are added to the power supply units for purposes of achieving backwards compatibility with the existing industry standard. A non-limiting example of a suitable AC interconnect is the IEC 60309. The IEC 60309 has higher AC current capabilities than the IEC 60320.  FIG. 1  is a high-level schematic that illustrates the use of IEC 60309 as an AC interconnect for a PSU, according to certain embodiments. 
     According to certain embodiments,  FIG. 1  shows a PSU chassis  102 , an AC interconnect  100  that includes a power cable  106 , AC plug  110 , an IEC 60309 plug  108  that plugs into IEC 60309 receptacle  104 . IEC 60309 receptacle  104  is on PSU chassis  102 . Voltage drops at high currents across a single IEC 60320 C13 AC cable are reduced. Less heat is dissipated than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  110  shown in  FIG. 1  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. Some non-limiting examples of AC plug types are shown in  FIG. 2 . 
       FIG. 2  illustrates international plug types  202 ,  204 ,  206 ,  208  and  210 , according to certain embodiments. The embodiments are not limited to the international plug types shown in  FIG. 2 . 
     As previously mentioned, the embodiments are not limited to the IEC 60309 as a suitable AC interconnect. Various AC interconnect schemes can be used in the embodiments.  FIGS. 3-6  show a variety of AC interconnect schemes that can replace the IEC 60320 C13 power cord inserted into a single IEC 60320 C14 inlet, according to certain embodiments. 
     According to certain embodiments,  FIG. 3A  illustrates the use of a terminal block in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 3A  shows a PSU chassis  302 , an AC interconnect  300  that includes an AC power cable  312 , AC plug  314 , a terminal cover  308  and spade or lug terminals  310  that are screwed onto a terminal block  304  mounted on a printed circuit board  306  (PCB) inside PSU chassis  302 . For example, the stripped ends of each wire comprising AC power cable  312  may be crimped or soldered to the appropriate end of each spade or lug terminal  310 . Terminal block  304  replaces the standard IEC 60320 inlet. Terminal cover  308  may be a removable cover that meets international electrical safety standards. The AC power cable  312  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). In such an AC interconnect scheme, the voltage drops at high currents across the AC cable are reduced. Less heat is dissipated in terminal block  304  than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  314  shown in  FIG. 3A  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. As previously mentioned, non-limiting examples of AC plug types are shown in  FIG. 2 . According to certain other embodiments, spade terminals  310  can be bolted directly to the printed circuit board  306  (PCB) inside PSU chassis  302 . In such an embodiment, terminal block  304  is not used. According to yet other embodiments, no spade or lug terminals are used for connecting to some types of terminal blocks. For example,  FIG. 3B  shows a terminal block  316 . Terminal block  316  includes wire receptacles  318  that can receive stripped ends of each wire comprising a power cable (not shown in  FIG. 3B ). Such stripped ends can be tinned with solder, for example, and are secured to terminal block  316  by tightening set screws  320  to clamp down on the stripped ends. Terminal block  316  can be secured to the printed circuit board (PCB) inside PSU chassis by solder pins  322 . 
     According to certain embodiments,  FIG. 4  illustrates the use of a circular connector in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 4  shows a PSU chassis  402 , an AC interconnect  400  that includes an AC power cable  408 , AC plug  410  and a circular free hanging connector  406  that mates with circular panel mount connector  404  mounted on a PSU chassis  402 . For example, the stripped ends of each wire comprising AC power cable  408  can be soldered or crimped to the pins (not shown) that can be inserted into circular free hanging connector  406 . Circular free hanging connector  406  and circular panel mount connector  404  may have threaded housings so that circular free hanging connector  406  can be screwed onto the circular panel mount connector  404 , for example. As another example, circular free hanging connector  406  and the circular panel mount connector  404  have bayonet type housings to allow the circular free hanging connector  406  to be mated to the circular panel mount connector  404 . Circular panel mount connector  404  replaces the standard IEC 60320 inlet. The AC power cable  408  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). In such an AC interconnect scheme, the voltage drops at high currents across the AC cable are reduced. Less heat is dissipated in circular panel mount connector  404  than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  410  shown in  FIG. 4  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. As previously mentioned, non-limiting examples of AC plug types are shown in  FIG. 2 . 
     According to certain embodiments,  FIG. 5  illustrates the use of a rectangular connector in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 5  shows a PSU chassis  502 , an AC interconnect  500  that includes an AC power cable  508 , AC plug  510  and a rectangular free hanging connector  506  that mates with rectangular panel mount connector  504  mounted on a PSU chassis  502 . For example, the stripped ends of each wire comprising AC power cable  508  can be soldered or crimped to the pins (not shown) that can be inserted into rectangular free hanging connector  506 . Rectangular free hanging connector  506  can be inserted into the complementary rectangular panel mount connector  504  (pins not shown). Rectangular free hanging connector  506  and complementary rectangular panel mount connector  504  can have housings that employ mechanical latching mechanism, or flexible plastic latches or threaded fasteners, for example. Rectangular panel mount connector  504  replaces the standard IEC 60320 inlet. The AC power cable  508  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). In such an AC interconnect scheme, the voltage drops at high currents across the AC cable are reduced. Less heat is dissipated in rectangular panel mount connector  504  than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  510  shown in  FIG. 5  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. As previously mentioned, non-limiting examples of AC plug types are shown in  FIG. 2 . 
     According to certain embodiments,  FIG. 6  illustrates the use of a direct connection in an AC interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 6  shows a PSU chassis  602 , chassis rear shown removed  604 , an AC interconnect  600  that includes an AC power cable  608 , AC plug  610  and the stripped ends  606  of AC cable soldered or bolted to the printed circuit board in the PSU chassis  602 . The stripped ends  606  that are soldered or bolted to the printed circuit board replace the standard IEC 60320 inlet. The AC power cable  608  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). In such an AC interconnect scheme, the voltage drops at high currents across the AC cable are reduced. Less heat is dissipated in the stripped ends  606  that are soldered or bolted to the printed circuit board than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  610  shown in  FIG. 6  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. As previously mentioned, non-limiting examples of AC plug types are shown in  FIG. 2 . 
     According to certain embodiments,  FIG. 7  illustrates the use of a direct connection in an AC interconnect scheme in conjunction with a connector to join a portion of the AC cable that includes the AC plug to the rest of the AC cable connected to the printed circuit board for use with a PSU that is compatible with PCs and workstations.  FIG. 7  shows a PSU chassis  702 , chassis rear shown removed  704 , an AC interconnect  700  that includes an AC power cable  708 , AC plug  710 , mated pair of connectors  712 , and the stripped ends  706  of AC cable soldered or bolted to the printed circuit board in the PSU chassis  702 . The stripped ends  706  that are soldered or bolted to the printed circuit board replace the standard IEC 60320 inlet. The mated pair of connectors  712  connect the portion of the AC cable  708  that includes the AC plug to the rest of the AC cable connected to the printed circuit board. The AC power cable  708  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). In such an AC interconnect scheme, the voltage drops at high currents across the AC cable are reduced. Less heat is dissipated in the combination of the connector joined to complementary mating connector  712  and AC cable soldered internally  706  than in the standardized single IEC 60320 C14 chassis plug inlet. Overall efficiencies are thus increased. The AC plug  710  shown in  FIG. 7  is a standard AC plug that is compatible with US electrical standards. However, the AC plug can be any international plug type depending on the country in which the PSU is used. As previously mentioned, non-limiting examples of AC plug types are shown in  FIG. 2 . 
     According to certain embodiments,  FIGS. 8A-C  illustrate the use of multiple connectors associated with AC power cables on a PSU. The implementation illustrated in  FIGS. 8A-C  present an implementation that is backward compatible with the existing IEC320 systems and also allow an option for installing a high efficiency AC power cable, thus limiting the voltage drop and thereby reducing the power wasted in the interconnect, according to certain embodiments.  FIG. 8A  shows two dissimilar inlets  804  and  806  mounted adjacent to one another on a PSU chassis  802 . As a non-limiting example, inlet  806  may the standard IEC 60320 C14 and inlet  804  is an inlet with a higher current carrying capacity (e.g., IEC 60309 C14 inlet, terminal block, circular panel mount connector, or rectangular panel mount connector). Such a configuration allows a user to select between the standard IEC 60320 C14 inlet  806  and the more robust inlet  804  that has a higher current carrying capacity. 
     According to certain embodiments,  FIGS. 8B and 80  show a sliding door  808 . Sliding door  808  is configured such that either inlet  804  or inlet  806  can be exposed for use. Sliding door  808  is a safety feature and covers the inlet that is not in use. 
     According to certain embodiments, modular cables for direct current (DC) output from the PSU are designed with DC modular cable interconnect schemes. Each PSU may have multiple modular cables for use with various peripherals of the computer. According to certain embodiments, connectors with lower contact resistance coupled with wire of higher diameter are used to lower voltage drops and thus lower power losses. According to certain embodiments, a given DC modular cable has a connector that has a large contact area at the end portion of the DC modular cable that connects to the PSU. The other end of the DC modular cable that does not connect to the PSU ends in a connector that is compatible with existing peripheral implementations. Further, each DC modular cable has wiring of less than AWG 16 gauge. Such DC modular cable interconnect schemes reduce series resistance, increase reliability and reduce cost. Various DC modular cable interconnect schemes can be used in the embodiments.  FIGS. 9-15  show a variety of DC cable interconnect schemes. For ease of explanation, each of  FIGS. 9-15  show only one connector on the PSU chassis. However, the embodiments are not limited to only one modular cable. According to some embodiments, the PSU can include an array of connectors of various types or the same type for use with a corresponding set of DC modular cables. Further, the interconnect schemes as shown in  FIGS. 9-15  include at least two conductors, one for power and one for ground, according to certain embodiments. For example, the interconnect uses even multiples of two conductors (multiple power-ground pairs). However, there may be specific circumstances in which an odd number of conductors would be employed.  FIGS. 12 -15  show two conductors for each interconnect. 
     According to certain embodiments,  FIG. 9  illustrates the use of a terminal block in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 9  shows a PSU chassis  902 , a DC modular cable interconnect  900  that includes a power cable  912 , a connector  914  (not shown) for connecting to a computer peripheral and spade lugs  910  that are screwed onto a terminal block  904  mounted on a printed circuit board (PCB) inside PSU chassis  902 . Stripped ends of each wire comprising one end of power cable  912  can be crimped or soldered onto spade lugs  910 , for example. Power cable  912  has conductors with a wire suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). According to certain embodiments, no spade or lug terminals are used for connecting to some types of terminal blocks. For example,  FIG. 3B  shows a terminal block  316 . Terminal block  316  includes wire receptacles  318  that can receive stripped ends of each wire comprising a power cable (not shown in  FIG. 3B ). Such stripped ends can be tinned with solder, for example, and are secured to terminal block  316  by tightening set screws  320  to clamp on the stripped ends. Terminal block  316  can be secured to the printed circuit board (PCB) inside PSU chassis by solder pins  322 . 
     According to certain embodiments,  FIG. 10  illustrates the use of a circular connector in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 10  shows a PSU chassis  1002 , a DC modular cable interconnect  1000  that includes a power cable  1008 , a connector  1010  (not shown) for connecting to a computer peripheral and a circular free hanging connector  1006  that mates with circular panel mount connector  1004  mounted on a PSU chassis  1002 . Stripped ends of each wire comprising power cable  1008  can be soldered or crimped to the pins (not shown) that can be inserted into circular free hanging connector  1006 , for example. Circular free hanging connector  1006  and circular panel mount connector  1004  may have threaded housings so that circular free hanging connector  1006  can be screwed onto the circular panel mount connector  1004 , for example. As another example, circular free hanging connector  1006  and the circular panel mount connector  1004  have bayonet type housings to allow the circular free hanging connector  1006  to be mated to the circular panel mount connector  1004 . The power cable  1008  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). 
     According to certain embodiments,  FIG. 11  illustrates the use of a rectangular connector in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 11  shows a PSU chassis  1102 , a DC modular cable interconnect  1100  that includes a power cable  1108 , connectors  1110  (not shown) for connecting to a computer peripheral and a rectangular free hanging connector  1106  that mates with rectangular panel mount connector  1104  mounted on a PSU chassis  1102 . For example, the stripped ends of each wire comprising one end of power cable  1108  can be soldered or crimped to the pins (not shown) that can be inserted into rectangular free hanging connector  1106 . Rectangular free hanging connector  1106  can be inserted into the complementary rectangular panel mount connector  1104  (pins not shown). Rectangular free hanging connector  1106  and complementary rectangular panel mount connector  1104  can have housings that employ mechanical latching mechanism, or flexible plastic latches or threaded fasteners, for example. The power cable  1108  has conductors with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). 
     According to certain embodiments,  FIG. 12  illustrates the use of a wave crimp connector in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 12  shows a PSU chassis  1202 , a DC modular cable interconnect  1200  that includes two power cables  1208  (one for DC voltage and the other for ground return), a connector  1210  (not shown) for connecting to a computer peripheral and a wave crimp connector  1206  that mates with wave crimp chassis mount connector  1204  mounted on a PSU chassis  1202 . Wave crimp connector  1206  can be inserted into the complementary wave crimp mount connector  1204 . Each power cable  1208  has a single flat cable conductor with a wire gauge suitable for low voltage drops at high currents (e.g., less than AWG 16 gauge). 
     According to certain embodiments,  FIG. 13  illustrates the use of a bus bar and clamp in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 13  shows a PSU chassis  1302 , a DC modular cable interconnect  1300  that includes two flat braided power cables  1308  (one for DC voltage and the other for ground return), connectors  1310  (not shown) for connecting to a computer peripheral and clamp connectors  1306  that can be clamped to corresponding bus bars connector  1304  mounted inside a PSU chassis  1302 . According to certain embodiments, the metal bus bars are such that wires of the DC modular cable can be secured to the bus bars by screwing, clamping, welding or soldering. The flat braided power cables  1308  are such that they are suitable for low voltage drops at high currents. According to certain embodiments, Litz wire can be used. According to certain embodiments, the aluminum bus bars can be nickel plated first, and then optionally plated with gold to achieve lower contact resistance. 
     According to certain embodiments,  FIG. 14  illustrates the use of an extended horizontal printed circuit board (PCB) in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 14  shows a PSU chassis  1402 , a DC modular cable interconnect  1400  that includes two flat power cables  1410  (one for DC voltage and the other for ground return), connectors  1412  (not shown) for connecting to a computer peripheral, and an extended horizontal PCB  1404  with PC fingers  1406 . The flat power cables  1410  are clamped onto PCB fingers  1406  using cable clamps  1408 . According to certain embodiments, the flat cables  1410  can be secured to the PCB fingers  1406  by screwing, clamping, welding or soldering. The flat power cables  1410  are such that they are suitable for low voltage drops at high currents. According to certain embodiments, Litz wire can be used. 
     According to certain embodiments,  FIG. 15  illustrates the use of an extended horizontal printed circuit board (PCB) in a DC modular cable interconnect scheme for use with a PSU that is compatible with PCs and workstations.  FIG. 15  shows a PSU chassis  1502 , a DC modular cable interconnect  1500  that includes two power cables  1510  (one for DC voltage and the other for ground return), connectors  1512  (not shown) for connecting to a computer peripheral, and an extended horizontal PCB  1504  with PC fingers  1506 . The power cables  1510  have lugs  1508  that are clamped onto PCB fingers  1506 . According to certain embodiments, the cables  1510  can be secured to the PCB fingers  1506  by screwing, clamping, welding or soldering. The power cables  1510  are such that they are suitable for low voltage drops at high currents. 
     According to certain embodiments, with respect to DC modular cables used with PSUs, instead of using a bundle of wires to hard wire the DC output electronics from a horizontally oriented PSU main PCB (horizontal PCB) containing the PSU&#39;s output electronics to a vertically oriented PCB (vertical connector PCB) where the modular cable connector outlets are mounted, various PCB interconnect schemes can be used as illustrated in  FIGS. 16-23  to increase reliability and efficiency of the PSU. According to some embodiments, such PCB interconnect schemes are low resistance interconnect schemes. For purposes of explanation, the embodiments are described using a vertically oriented connector PCB and a horizontally oriented PSU main PCB. However, the embodiments are not limited to such an orientation. 
     According to certain embodiments,  FIG. 16  illustrates the use of a pin interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 16  shows two vertical connector PCBs  1602  that are connected to horizontal PCB  1606  through a respective array of pins  1604 . Each vertical connector PCB is installed with one or more DC connector outlets  1603  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. According to certain embodiments, the respective array of pins  1604 , each of which is capable of carrying relatively high currents (on the order of a few amps), is soldered to its respective vertical connector PCB. Each vertical connector PCB is soldered to the horizontal PCB in the PSU which allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 17  illustrates the use of a high current connector array interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 17  shows two vertical connector PCBs  1702  each vertical connector PCB is installed with one or more DC connector outlets  1703  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. Soldered to each vertical connector PCB  1702  is a respective high current connector array  1704 . Each high current connector in the array  1704  comprises a large array of pins, each of which is capable of carrying relatively high currents (on the order of a few amps). Complementary mating connector arrays  1706  are soldered to the horizontal PCB  1708  in the PSU. Each vertical connector PCB  1702  can be connected to the horizontal PCB  1708  in the PSU by mating each high current connector array  1704  with its counterpart complementary mating connector array  1706 , which allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1.The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 18  illustrates the use of connector fingers array and high pin count connector array interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 18  shows two vertical connector PCBs  1802 . each vertical connector PCB is installed with one or more DC connector outlets  1803  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. Each vertical connector PCB  1802  is etched with a respective array of connector fingers  1804 . Respective complementary high pin count connector arrays  1806  are soldered to the horizontal PCB  1808  in the PSU. Each vertical connector PCB can be connected to the horizontal PCB in the PSU by mating each array connector fingers  1804  with its counterpart complementary high pin count connector arrays  1806 , which allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 19  illustrates the use of wide fingers connector array and corresponding milled slits interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 19  shows two vertical connector PCBs  1902 , each vertical connector PCB is installed with one or more DC connector outlets  1903  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. Each vertical connector PCB  1902  is etched or routed with a plurality of wide fingers  1904  separated by routed gaps, for example. Respective complementary slits  1906  are milled into the horizontal PCB  1908  in the PSU. Each vertical connector PCB can be connected to the horizontal PCB in the PSU by mating each of wide fingers  1904  with its counterpart complementary slit  1906  on the horizontal PCB  1908  and soldering the mated pair. The large trace areas on the wide fingers  1904  allow high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, the wide fingers  1904  and milled slits  1906  can be nickel plated first, and then optionally plated with gold to achieve lower contact resistance. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 20  illustrates the use of right angle metal bracket interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 20  shows two vertical connector PCBs  2002 , each vertical connector PCB is installed with one or more DC connector outlets  2003  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs.  FIG. 20  also shows a horizontal PCB  2008 . Each vertical connector PCB  2002  and the horizontal PCB  2008  includes respective plated areas  2006  to which are attached corresponding right angle metal brackets  2004 . Each plated area  2006  has at least one hole. For example, one edge of each right angle metal bracket  2004  makes contact with a corresponding copper area etched into each vertical PCB. On each right angle metal bracket  2004  may be installed two or more captive nuts. Screws may be inserted through the holes in the copper plated areas  2006  of each vertical PCB and horizontal PCB and tightened into each right angle metal bracket  2004  at the location of the corresponding captive nuts. Thus, each vertical connector PCB  2002  is connected to the horizontal PCB  2008  in the PSU and allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, the right angle metal brackets  2004  and plated areas  2006  can be nickel plated first, and then optionally plated with gold to achieve lower contact resistance. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 21  illustrates the use of straight metal brackets and corresponding milled slits interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 21  shows two vertical connector PCBs  2102 , each vertical connector PCB is installed with one or more DC connector outlets  2103  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. Each vertical connector PCB  2102  includes copper plated areas  2104  to which are attached corresponding straight metal brackets  2106 . Each plated area  2104  has at least one hole. For example, one edge of each straight metal bracket  2106  makes contact with a corresponding area etched into each vertical PCB. On each straight metal bracket  2106  may be installed one or more captive nuts at locations where the vertical PCB is to be secured to the straight metal brackets  2106 . Screws may be inserted through the holes in the copper plated areas  2104  of each vertical PCB and tightened into each metal bracket  2106  at the location of the corresponding captive nut. Respective complementary slits  2108  are milled into the horizontal PCB  2110  in the PSU. Each vertical connector PCB  2102  can be connected to the horizontal PCB  2110  in the PSU by mating each of the metal brackets  2106  into its counterpart complementary slit  2108  on the horizontal PCB  2110  and soldering the mated pair. According to certain embodiments, the metal brackets  2106  are plated with an alloy that allows them to be soldered into slits  2108 . According to certain embodiments straight metal brackets can be nickel plated first, and then optionally plated with gold to achieve lower contact resistance. Thus, each vertical connector PCB  2102  is connected to the horizontal PCB  2108  in the PSU and allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 22  illustrates the use of braided flat cable and corresponding milled slits interface between the horizontal PCB and the vertical connector PCB to replace the wire bundle that would have been used to hard wire the horizontal PCB to the vertical connector PCB in a PSU.  FIG. 22  shows two vertical connector PCBs  2202 , each vertical connector PCB is installed with one or more DC connector outlets  2203  to which DC modular cables can be connected. The embodiments are not limited to two vertical connector PCBs. Each vertical connector PCB  2202  includes copper plated areas  2204  to which are attached corresponding flat braided cables  2206 . Each plated area  2204  has at least one hole. For example, one edge of each flat braided cable  2206  makes contact with a corresponding area etched into each vertical PCB. Behind each flat braided cable  2206  may be installed flat washers and nuts (not shown) at locations where the vertical PCB is to be secured to the flat braided cables  2206 . Screws (not shown) may be inserted through the holes in the copper plated areas  2204  of each vertical PCB through each flat braided cable  2206  and flat washer (not shown) and secured by the corresponding nut (not shown). Respective complementary slits  2208  are milled into the horizontal PCB  2210  in the PSU. Each vertical connector PCB  2202  can be connected to the horizontal PCB  2210  in the PSU by mating each of the flat braided cables  2206  into its counterpart complementary slit  2208  on the horizontal PCB  2210  and soldering the mated pair. According to certain embodiments, the flat braided cables  2206  are plated with an alloy that allows them to be soldered into slits  2208 . According to certain embodiments metal brackets can be nickel plated first, and then optionally plated with gold to achieve lower contact resistance. Thus, each vertical connector PCB  2202  is connected to the horizontal PCB  2208  in the PSU and allows high currents to be transferred between vertical connector PCBs and the horizontal PCB with low voltage drops. According to certain embodiments, there are N+1 vertical boards, where N is equal to or greater than 1. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N vertical boards. 
     According to certain embodiments,  FIG. 23  illustrates the use of a plurality of connector arrays mounted directly on a horizontal PCB, the plurality of connector arrays for use as DC modular cable outlets.  FIG. 23  shows a PSU chassis  2302 , a horizontal printed circuit board (PCB)  2310  and a plurality of connector rows  2304  (only 2 rows are shown and wherein the plurality is two or more rows) mounted directly on a horizontal PCB  2310 . The plurality of connector rows  2304  is not limited to 2 rows. According to certain embodiments, there may be more than 2 rows. Each of the connectors in the connector rows  2304  serve as a DC modular cable outlet.  FIG. 23  shows one of the connector rows  2304  oriented horizontally while the other connector row  2304  is oriented vertically. According to certain embodiments, the plurality of connector rows  2304  may all be oriented vertically According to other embodiments, the first set of connector rows  2304  closest to the chassis wall (outermost row of connectors) is oriented horizontally while the rest of the plurality of connector rows  2304  are oriented vertically. According to certain other embodiments, the plurality of connector rows  2304  may be used in conjunction with N vertical boards as described herein with reference to  FIGS. 16-22 , where N is equal to or greater than 1. The plurality of connector rows  2304  are closer to the opening of the power supply chassis than the N vertical boards. The N−1th vertical board is closer to the opening of the power supply chassis than the Nth vertical board. The Nth vertical board has a greater height that the N−1th vertical board to allow DC connector outlets to be installed on each of the N vertical boards. According to certain embodiments, only one connector row  2304  is used in conjunction with N+1 vertical boards, where N is equal to or greater than 1. The single connector row  2304  is closer to the opening of the power supply chassis than the N+1 vertical boards. The Nth vertical board is closer to the opening of the power supply chassis than the N+1th vertical board. The N+1th vertical board has a greater height that the Nth vertical board to allow DC connector outlets to be installed on each of the N+1 vertical boards 
     In the foregoing specification, embodiments of the invention have been described with reference to numerous specific details that may vary from implementation to implementation. Thus, the sole and exclusive indicator of what the invention is and what is intended by the applicants to be the invention, is the set of claims that issue from this application, in the specific form in which such claims issue, including any subsequent correction. Any express definitions set forth herein for terms contained in such claims shall govern the meaning of such terms as used in the claims. Hence, no limitation, element, property, feature, advantage or attribute that is not expressly recited in a claim should limit the scope of such claim in any way. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.