Removable memory module coupling

Removeable couplings are provided for connecting a memory module to a host processor of an IHS (Information Handling System). The coupling includes electrical contacts and fasteners for positioning the electrical contacts within an empty memory slot of the IHS motherboard. The housing extends between two ends of the coupling and receives the memory module when the memory module is installed in the IHS. The positioned electrical contacts are then seated within the memory slot of the motherboard by the downward force applied by an administrator in installing the memory module to the coupling. The force applied in installing the memory module also serves to connect the electrical contacts of the coupling to a memory channel of the motherboard. The removeable coupling is not attached to the motherboard when the memory module is not installed in the IHS, thus eliminating signal stubs in the memory channel.

FIELD

This disclosure relates generally to Information Handling Systems (IHSs), and more specifically, to memory systems for IHSs.

BACKGROUND

IHSs may utilize one or more storage drives for persistent storage of data. IHSs may also utilize memory devices of various technologies for volatile data storge. For example, memory modules may be used to implement a system memory that is utilized by processing resources of the IHS in the execution of program instructions. In some instances, such memory modules may be replaceable, thus supporting the upgrading of an IHSs memory capabilities and addressing error conditions or other performance issues.

SUMMARY

In various embodiments, removeable couplings are provided for connecting a memory module to a host processor of an IHS (Information Handling System). The coupling may include: a plurality of electrical contacts; a plurality of fasteners for positioning the electrical contacts of the coupling within a memory slot of a motherboard of the IHS; and a housing that extends between two ends of the coupling and that receives the memory module when the memory module is installed in the IHS, wherein the positioned electrical contacts are seated within the memory slot of the motherboard by a force applied in installing the memory module, and wherein the force applied in installing the memory module connects the electrical contacts of the coupling to a memory channel of the motherboard, and wherein the coupling is not attached to the motherboard when the memory module is not installed in the IHS.

In some coupling embodiments, the housing of the coupling is manufactured in a prestressed state such that the electrical contacts of the coupling are in a convex arrangement when the coupling is not attached to the motherboard. In some coupling embodiments, the concave arrangement of the electrical contacts is converted to a concave arrangement of the electrical contacts though tightening of the fasteners. In some coupling embodiments, the concave arrangement of the electrical contacts is straightened by the force applied in installing the memory module in the coupling. In some coupling embodiments, the straightening of the electrical contacts of the coupling seats the electrical contacts uniformly within the memory slot of the motherboard. In some coupling embodiments, the memory channel is an underutilized memory channel prior to installation of the memory module via the coupling. In some coupling embodiments, a location of the memory slot of the motherboard for use with the coupling is selected such that there is no stub in the memory channel when the coupling is not attached to the motherboard. In some coupling embodiments, the memory module is a DIMM (Dual In-line Memory Module). In some coupling embodiments, the fasteners comprise compression screws that are received by threaded holes in the motherboard of the IHS when the coupling is attached to the motherboard.

In various additions embodiments, systems are provided that may include: a motherboard of an IHS (Information Handling System), wherein the motherboard comprises a processor; and a removeable coupling for connecting a memory module to the processor, the coupling comprising: a plurality of electrical contacts; a plurality of fasteners for positioning the electrical contacts of the coupling within a memory slot of a motherboard of the IHS; and a housing that extends between two ends of the coupling and that receives the memory module when the memory module is installed in the IHS, wherein the positioned electrical contacts are seated within the memory slot of the motherboard by a force applied in installing the memory module, and wherein the force applied in installing the memory module connects the electrical contacts of the coupling to a memory channel of the motherboard, and wherein the coupling is not attached to the motherboard when the memory module is not installed in the IHS.

In some system embodiments, the housing of the coupling is manufactured in a prestressed state such that the electrical contacts of the coupling are in a concave arrangement when the coupling is not attached to the motherboard. In some system embodiments, the concave arrangement of the electrical contacts is converted to a convex arrangement of the electrical contacts though tightening of the fasteners. In some system embodiments, the convex arrangement of the electrical contacts is straightened by the force applied in installing the memory module in the coupling, and wherein the straightening of the electrical contacts of the coupling seats the electrical contacts uniformly within the memory slot of the motherboard. In some system embodiments, the memory channel is an underutilized memory channel of the motherboard prior to installation of the memory module via the coupling. In some system embodiments, a location of the memory slot of the motherboard for use with the coupling is selected such that there is no stub in the memory channel when the coupling is not attached to the motherboard. In some system embodiments, the memory module is a DIMM (Dual In-line Memory Module).

In various additional embodiments, motherboards of an IHS may include: a processor; a plurality of memory channels connecting the processor to memory slots for receiving memory modules; and a plurality of memory slots that are configured to receive a removeable coupling for connecting a memory module to the processor, the coupling comprising: a plurality of electrical contacts; a plurality of fasteners for positioning the electrical contacts of the coupling within a memory slot of a motherboard of the IHS; and a housing that extends between two ends of the coupling and that receives the memory module when the memory module is installed in the IHS, wherein the positioned electrical contacts are seated within the memory slot of the motherboard by a force applied in installing the memory module, and wherein the force applied in installing the memory module connects the electrical contacts of the coupling to a memory channel of the motherboard, and wherein the coupling is not attached to the motherboard when the memory module is not installed in the IHS.

In some motherboard embodiments, a location of the memory slot of the motherboard for use with the coupling is selected such that there is no stub in the memory channel when the coupling is not attached to the motherboard. In some motherboard embodiments, the memory module is a DIMM (Dual In-line Memory Module). In some motherboard embodiments, the memory channel is an underutilized memory channel of the motherboard prior to installation of the memory module via the coupling.

DETAILED DESCRIPTION

For purposes of this disclosure, an IHS may include any instrumentality or aggregate of instrumentalities operable to compute, calculate, determine, classify, process, transmit, receive, retrieve, originate, switch, store, display, communicate, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an IHS may be a personal computer (e.g., desktop or laptop), tablet computer, mobile device (e.g., Personal Digital Assistant (PDA) or smart phone), server (e.g., blade server or rack server), a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. An IHS may include Random Access Memory (RAM), one or more processing resources such as a Central Processing Unit (CPU) or hardware or software control logic, Read-Only Memory (ROM), and/or other types of nonvolatile memory.

Additional components of an IHS may include one or more disk drives, one or more network ports for communicating with external devices as well as various I/O devices, such as a keyboard, a mouse, touchscreen, and/or a video display. An IHS may also include one or more buses operable to transmit communications between the various hardware components. An example of an IHS is described in more detail below.FIG.1shows various internal components of an example IHS configured to implement the provided embodiments. It should be appreciated that although certain embodiments described herein may be discussed in the context of a desktop or rack-mounted server, other embodiments may be utilize various other types of IHSs.

FIG.1is a block diagram depicting certain components of an IHS100configured to utilize a memory module compression coupling according to various embodiments. IHS100includes one or more processors101, such as a Central Processing Unit (CPU), that execute code retrieved from a system memory105. Although IHS100is illustrated with a single processor101, other embodiments may include two or more processors, that may each be configured identically, or to provide specialized processing functions. Processor101may include any processor capable of executing program instructions, such as an Intel Pentium™ series processor or any general-purpose or embedded processors implementing any of a variety of Instruction Set Architectures (ISAs).

In the embodiment ofFIG.1, the processor101includes an integrated memory controller118that may be implemented directly within the circuitry of the processor101, or the memory controller118may be a separate integrated circuit that is located on the same die as the processor101. In certain embodiments, the memory controller118may be separate from the processor(s)101and may instead communicate with the processor(s)101via the chipset102. The memory controller118may be configured to manage the transfer of data to and from the system memory105of the IHS100. In certain embodiments, the memory controller118may also be responsible for refreshing any volatile memory components of the system memory105. The memory controller118may be configured to manage the transfer of data to and from the system memory105of the IHS100via a high-speed memory interface104, such as a DDR4 (Double Data Rate Four) memory interface or such as a DDR5 (Double Data Rate Five) memory interface.

The system memory105that is coupled to processor101via the memory bus104provides the processor101with a high-speed memory that may be used in the execution of computer program instructions by the processor101. Accordingly, system memory105may include memory components, such as dynamic RAM (DRAM) memory modules, suitable for supporting high-speed memory operations by the processor101. As described in greater detail below, the system memory105according to embodiments supports use of removeable compression coupling by which memory modules, such as DIMMs (dual in-line memory modules), may be installed in empty slots of the system memory105in order to expand its capabilities. Through the use of compression coupling embodiments, IHS100may support expansion of system memory capabilities. However, as described in additional detail below, through removal of the compression coupling when a memory slot is not in use, signal integrity is improved within the signaling pathways of the system memory150.

IHS100utilizes a chipset103that may include one or more integrated circuits that are connected to processor101. In the embodiment ofFIG.1, processor101is depicted as a component of chipset103. In other embodiments, all of chipset103, or portions of chipset103may be implemented directly within the integrated circuitry of the processor101. Chipset103provides the processor(s)101with access to a variety of resources accessible via bus102. In IHS100, bus102is illustrated as a single element. Various embodiments may utilize any number of buses to provide the illustrated pathways served by bus102.

As illustrated, a variety of resources may be coupled to the processor(s)101of the IHS100through the chipset103. For instance, chipset103may be coupled to a network interface109that may support different types of network connectivity. In certain embodiments, IHS100may include one or more Network Interface Controllers (NICs), each of which may implement the hardware required for communicating via a specific networking technology, such as Wi-Fi, BLUETOOTH, Ethernet and mobile cellular networks (e.g., CDMA, TDMA, LTE). As illustrated, network interface109may support network connections by wired network controllers122and wireless network controller123. Each network controller122,123may be coupled via various buses to the chipset103of IHS100in supporting different types of network connectivity, such as the network connectivity utilized by applications of the operating system of IHS100.

Chipset103may also provide access to one or more display device(s)113via graphics processor107. In certain embodiments, graphics processor107may be comprised within a video or graphics card or within an embedded controller installed within IHS100. In certain embodiments, graphics processor107may be integrated within processor101, such as a component of a system-on-chip. Graphics processor107may generate display information and provide the generated information to one or more display device(s)113coupled to the IHS100. The one or more display devices113coupled to IHS100may utilize LCD, LED, OLED, or other display technologies. Each display device113may be capable of receiving touch inputs such as via a touch controller that may be an embedded component of the display device113or graphics processor107, or may be a separate component of IHS100accessed via bus102. In embodiments where IHS100is a laptop, tablet, 2-in-1 convertible device, or mobile device, display device113may be an integrated display device. In some embodiments, IHS100may be a hybrid laptop computer that includes dual integrated displays incorporated in both of the laptop panels.

In certain embodiments, chipset103may utilize one or more I/O controllers110that may each support hardware components such as user I/O devices112. For instance, I/O controller110may provide access to one or more user I/O devices110such as a keyboard, mouse, touchpad, touchscreen, microphone, speakers, camera and other input and output devices that may be coupled to IHS100. Each of the supported user I/O devices112may interface with the I/O controller110through wired or wireless connections. In certain embodiments, sensors accessed via I/O controllers110may provide access to data describing environmental and operating conditions of IHS100.

Chipset103also provides processor101with access to one or more storage devices119. In various embodiments, storage device119may be integral to the IHS100, or may be external to the IHS100. In certain embodiments, storage device119may be accessed via a storage controller that may be an integrated component of the storage device. Storage device119may be implemented using any memory technology allowing IHS100to store and retrieve data. For instance, storage device119may be a magnetic hard disk storage drive or a solid-state storage drive. In certain embodiments, storage device119may be a system of storage devices, such as a cloud drive accessible via network interface109.

As illustrated, IHS100also includes a BIOS (Basic Input/Output System)117that may be stored in a non-volatile memory accessible by chipset103via bus102. In some embodiments, BIOS117may be implemented using a dedicated microcontroller coupled to the motherboard of IHS100. In some embodiments, BIOS117may be implemented as operations of embedded controller126. Upon powering or restarting IHS100, processor(s)101may utilize BIOS117instructions to initialize and test hardware components coupled to the IHS100. The BIOS117instructions may also load an operating system for use by the IHS100. The BIOS117provides an abstraction layer that allows the operating system to interface with the hardware components of the IHS100. The Unified Extensible Firmware Interface (UEFI) was designed as a successor to BIOS. As a result, many modern IHSs utilize UEFI in addition to or instead of a BIOS. As used herein, BIOS is intended to also encompass UEFI.

Some IHS100embodiments may utilize an embedded controller126that may be a motherboard component of IHS100and may include one or more logic units. In certain embodiments, embedded controller126may operate from a separate power plane from the main processors101, and thus from the operating system functions of IHS100. In some embodiments, firmware instructions utilized by embedded controller126may be used to operate a secure execution environment that may include operations for providing various core functions of IHS100, such as power management and management of certain operating modes of IHS100.

In various embodiments, an IHS100does not include all of the components shown inFIG.1. In various embodiments, an IHS100may include various additional components in addition to those that are shown inFIG.1. Furthermore, some components that are represented as separate components inFIG.1may in certain embodiments instead be integrated with other components. For example, in certain embodiments, all or a portion of the functionality provided by the illustrated components may instead be provided by components integrated into the processor101as systems-on-a-chip.

FIG.2is block diagram depicting two sides of a removeable memory module200. As described, in existing memory systems, a removeable memory module200is plugged into a system memory socket that is permanently fixed to the motherboard of an IHS, such as a Through-Hole and Surface Mount memory sockets that are permanently fixed to the motherboard through soldering. The replaceable memory module200may be a two-sided memory module that includes components on the front side205and the back side210. Each side of the removeable memory module200includes electrical contacts215, that may be referred to as pins, along the bottom edge. In existing systems, memory module200is installed through mating of pins215with corresponding contacts of a system memory socket that is permanently fixed to the motherboard of an IHS. In embodiments, the pins215of a removeable memory module200instead mate with corresponding pins of a compression coupling that may be attached to the motherboard of an IHS as needed when a removeable memory module200is being added to an IHS. The number, type and configuration of the pins215of a removeable memory module200may vary based on the type of memory interface being utilized. Through the electrical contact provided by pins215, the removeable memory module200may support one or more memory channels utilized by the memory controller of an IHS, such as described above.

As illustrated inFIG.2, a removeable memory module200may include a controller220that may be used to offload certain functions from the processor and/or to implement features supported by the removeable memory module200. In various embodiments, the controller220may include a processing component such as a microprocessor, microcontroller, application-specific integrated circuit (ASIC), or field-programmable gate array (FPGA) that is mounted on the printed circuit board from which the memory module200is formed. In some instances, the memory module200includes primary memory chips230on the front side205and secondary memory chips235on the second side210. In certain embodiments, all of the primary and secondary memory chips230and235are the same type of high-speed memory suitable for system memory, such as DRAM. In certain other embodiments, the primary memory chips230may be a high-speed volatile memory, such as DRAM, and the secondary memory chips235may be non-volatile memory that is implemented using memory technologies such as MRAM, which may provide high-speed performance suitable for use in system memory while also providing non-volatile storage.

FIG.3Ais schematic diagram depicting certain aspects of a memory system that includes eight memory modules, such as DIMMs, that are utilized via four memory channels. The illustrated memory system includes a processor350that may utilize one or more memory controllers in operating the eight memory modules. Processor350may be any processor capable of executing program instructions, such as the general-purpose system processor of an IHS. As described with respect to memory controller118ofFIG.1, one or more memory controllers may be integrated directly within the circuitry of processor350, or may be implemented as separate processing components from processor350. Processor350may utilize these memory controllers to manage the transfer of data to and from the removeable memory modules. In some instances, processor350may utilize separate memory controllers to support each of the memory channels355a-dthat are supported by the memory system.

In the illustrated memory system, processor350supports four memory channels355a-d, each of which supports two memory modules that are connected in series via a respective memory channel to the processor, or to a memory controller operating on behalf of the processor. In existing memory systems, each of the eight memory modules in all four memory channels355a-dare coupled to the motherboard of an IHS via a memory socket, such as a DIMM motherboard memory socket, that is permanently fixed to the motherboard and that receives a memory module. In typical IHSs, all eight of the memory modules in all four memory channels355a-dmay be manually removed and replaced by an administrator. Additionally, some IHSs may be manufactured and delivered with one or more of the motherboard memory sockets remaining empty, thus supporting capacity for additionally memory modules to be added to the memory system at a later time.

FIG.3Bis cutaway circuit diagram depicting signaling pathways in existing memory systems. The illustrated memory system includes a processor310that utilizes a set of removable memory modules335a-f, such as described with regard toFIG.2. The processor310is mounted on a printed circuit board305, such as a motherboard. The processor310communicates with the removable memory modules335a-fvia traces315that each extend within the printed circuit board305from the processor310to an individual connector by which each of the removable memory modules335a-fis coupled to the printed circuit board305. In existing systems, the sockets that receive the removable memory modules335a-fare permanently fixed to a printed circuit board305. For instance, during manufacture of the printed circuit board305in existing systems, the socket340cthat receives memory module335ais permanently fixed to the printed circuit board305.

As described, memory systems may utilize channels by which groups of memory modules may be accessed concurrently. In the system illustrated inFIG.3B, the memory system supports two memory modules per channel (i.e., 2 DPC (“DIMMS Per Channel”)). For instance, inFIG.3B, one memory channel is implemented by a trace that extends from the processor310and connects the first two removable memory modules335aand335b. In the same manner, a second memory channel is implemented by a trace that extends from the processor310and connects to the next two removable memory modules335cand335d. As indicated inFIG.3B, the first two memory channels are a fully loaded section320of system memory, where two memory modules335a-band335c-dare installed in each of the connectors supporting these memory channels.

However, in some instances, a motherboard may be manufactured to support two memory modules per channel (i.e., 2 DPC), but only a single memory module is installed in some of these channels, such that it is effectively operating at 1 DPC. This particular scenario is illustrated in the second section325of the illustrated memory system ofFIG.3B. In this second section325of system memory, only a single removable memory module is installed in each of the channels. As such, removable memory module335eis the only memory module in its channel, with the other memory socket340aof this channel left unoccupied. In the same manner, removable memory module335fis the only memory module in its channel, with the other memory socket340bof this channel also left unoccupied. As described, such unoccupied memory sockets340aand340bmay be left empty during manufacture of the printed circuit board305in order to support expansion of the memory capabilities of the system. In other instances, memory sockets340aand340bmay be unoccupied as a result of system administration that removed memory modules from these two sockets.

Regardless of the reason for the unoccupied memory sockets340a-b, in existing systems where memory sockets are permanently fixed to a printed motherboard, leaving any of these fixed memory sockets unoccupied results in a stub in the motherboard traces used to support these fixed memory sockets. For instance, in the memory channel of removable memory module335e, a stub portion330aof the memory channel branches from the trace used by memory module335e. The stub portion330aof the trace extends vertically through the printed circuit board305and into the unoccupied socket340a. The same manner, the stub portion330bof the memory channel of memory module335fextends through the printed circuit board305and through unoccupied socket340b.

In existing memory systems that utilize permanently fixed memory sockets, such signal stubs330a-bresulting from unoccupied memory modules significantly degrade the performance of the partially utilized memory channels in use by the memory modules335e-f. The loss of signal integrity in these partially utilized memory channels can be significant due to the length of the signal stubs330a-bthat result from the unoccupied memory sockets340a-b. The length of signal stubs, such as those illustrated in the existing system ofFIG.3B, may extend 150-200 mils through the printed circuit board and may extend an additional 150-200 mils through the fixed memory socket340a-b. When data is transmitted along a memory channel that includes unoccupied memory socket340a-b, the transmitted signal is reflected within the respective stub portion330a-bof the memory channel trace and subsequently withing the rest of the memory channel. Such reflected signal information diminishes the integrity of the signals being transmitted within the memory channel, where the amount of information loss due to signal distortion is proportional to the length of the stub portion330a-bof the trace.

FIG.4Ais a side-view illustration of an uninstalled memory module compression coupling400according to embodiments. The coupling400includes a housing410that receives electrical contacts along the bottom edge of a replaceable memory module, such as a DIMM, within a groove along the top of the housing410, where the groove that receives the memory module extends the length of the housing410. Once the compression coupling400has been fastened to the motherboard and a memory module has been installed within the groove of the coupling400, locking arms420a-bon each end of the housing410may be used to secure the memory module in place. As illustrated inFIG.4A, fastening screws415a-bmay also be located at each and of the housing410, where such fastening screws415a-bmay be used to positioning the compression coupling400to a motherboard memory slot, where it will be attached for use during intervals when a memory module will be installed and in use as a component of a memory system of an IHS. Other embodiments may utilize various other mechanisms instead of the illustrated fastening screws415a-bfor positioning the compression coupling400on a motherboard.

As described, existing memory systems utilize memory sockets that are permanently fixed to a motherboard, thus resulting in signal stubs within memory channels that include unoccupied memory sockets. In embodiments, removable compression coupling400may be manually positioned on a motherboard, such as using fastening screws415a-b, when a memory module is being added to the memory system of an IHS. Accordingly, when a memory module is removed from the memory system, the compression coupling400used to install the memory module is also removed from the motherboard, such as by loosening the fastening screws415a-b. As described in additional detail below, by removing a compression coupling400once a memory module is removed from a memory slot, or by leaving that motherboard memory slot empty during manufacture of the motherboard, signal stubs within underutilized memory channels are eliminated by embodiments.

As described, the housing410that receives a memory module extends between the two ends of a compression coupling400. Two physical states of the housing410are illustrated inFIG.4A. In the state corresponding to405a, the housing410extends in a straight line between the two ends of the compression coupling such that the compression contacts435on the bottom of the housing410can be aligned in a plane that is parallel with the motherboard. However, in some embodiments, compression couplings400may be manufactured in a second state that is prestressed such that the compression contacts435on the lower edge of the housing410are aligned in a convex shape405cwhen the coupling is not in use and thus not installed. Due to this prestressed manufacture of the coupling, the convex shape405cof the lower edge of the housing410is thus the natural shape of the housing when the compression coupling400is not installed and not attached to a motherboard.

InFIG.4B, compression coupling400is again illustrated in two different physical states. As inFIG.4A, in state405a, the housing410extends in a straight line such that the compression contacts435can be aligned parallel with the motherboard.FIG.4Balso illustrates a third state where the compression contacts435on the lower edge of the housing410are aligned in a concave shape405b. This concave shape405bof the compression contacts is achieved through fastening the compression coupling400to a motherboard memory slot using the screws415a-bat each end of the central housing410. InFIG.4B, in installing the compression coupling400, fastening screws415a-bhave been driven into the coupling and into holes provided by the motherboard at the two ends of a memory slot that is compatible with the described embodiments.

In installing the compression coupling400, an administrator may locate and align the coupling at a precise location on the motherboard that corresponds to an empty memory slot that is compatible with embodiments, where the empty memory slot is wired to operate using a memory channel that is presently underutilized. In some embodiments, the bottom surface of the compression coupling400below the locking arms420a-bmay include features that fit together with corresponding features of the motherboard, such as plastic pins that protrude downward from the bottom of the compression coupling400and that are received by corresponding holes of the motherboard. When aligned and located by an administrator using such features, the compression contacts435(which are still arranged in a convex shape405c) are each aligned with corresponding vias or other electrical contacts on the motherboard. In some instances, when the compression coupling is aligned and ready for fastening to the motherboard, each of the compression contacts435be mated, at least partially, through a downward force by the administrator with a via or other electrical contact of the motherboard.

With the compression contacts435still arranged in a convex shape405c, an administrator aligns and locates the compression coupling within an empty memory slot that includes structures, such as threaded holes, that receive the fastening screws415a-bof the compression coupling400. Once the coupling400is aligned, the administrator drives the fastening screws415a-binto the motherboard, either by rotating the fastening screws415a-bby hand, or using a hand tool or power tool to rotate the fastening screws415a-b. In using the fastening screws415a-bto attach the compression coupling to the motherboard, the compression contacts435of the coupling transition from the convex shape405cofFIG.4Ato the concave shape405bofFIG.4B. The tightening of fastening screws415a-bcounteracts the prestressed forces that generate the convex shape405cof the compression contacts435, thus deflecting the housing410upward to the concave shape405bwhile maintaining the individual compression contacts435above corresponding vias or other electrical contacts of the motherboard. Once the fastening screws415a-bhave been tightened, the compression contacts435are now aligned in the concave shape405bofFIG.4B, with some or all of the compression contacts still held in place through contact forces that keep individual compression contacts mated to varying degrees with the vias or other electrical contacts of the motherboard. In some embodiments, the amount of force that is required to deflect the housing of the compression coupling may be selected such that the force generated by tightening the fastening screws415a-bis sufficient to overcome the forces that generate the convex shape405cof the uninstalled compression contacts435. In some embodiments, amount of deflection of the concave shape405bof the compression contacts435that results from tightening fasteners415a-bmay be selected such that the sum of the contact forces that remain holding some or all of the compression contacts at least partially coupled to motherboard vias remains sufficient to keep the compression coupling in place.

With the compression coupling attached to the motherboard by an administrator in this manner, the concave line of compression contacts435are each mated to varying degrees with vias or other electrical contacts of the motherboard. Each of the compression contacts435may thus be in electrical contact with the motherboard, but the force retaining each of the compression contacts may be non-uniform. Due to the concavity of the compression contacts435, contacts closer to the two ends of the housing410may be retained by greater contact forces when compared to compression contacts at the center of the housing. The sum of these non-uniform forces is nonetheless sufficient to maintain the compression coupling400in place while the administrator installs a removeable memory module425in the compression coupling, such as illustrated inFIG.4C, and simultaneously seats the compression coupling in its attachment to the motherboard.

FIG.4Cis an illustration of a removable memory module installed in a compression coupling according to embodiments. InFIG.4C, a removable memory module425, such as a DIMM, has been inserted within the groove on the upper surface of the housing410. As described, when a memory module is being added to an IHS, a compression coupling400may be placed within an empty system memory slot that is compatible with embodiments described herein and that is connected to a memory channel that is presently underutilized. With the compression contacts435aligned in the concave shape405bofFIG.4Band each connected by varying degrees of contact force to the motherboard, the administrator places a memory module within the top groove of the housing410. In some cases, the administrator may locate and align the memory module425within the groove along the top of the housing410using corresponding features of the groove and of the electrical contacts430along the bottom edge of memory module425. Once the and the memory module425has been positioned correctly within the housing410, the administrator applies a downward force on the memory module425, and thus on the housing410, which is initially still in the concave shape405bofFIG.4B. Due to continued application of force by the administrator, the resistive force of the concave-shaped compression contacts435is overcome until the housing410is straightened, to shape405a. In addition, the application of force by the administrator also results in each of the compression contacts435along the bottom of the housing410being uniformly seated and attached to the corresponding electrical contacts on the motherboard.

In many instances, the manufacture of electrical connection structures, such as pins used as compression contacts435and such as via holes of a printed circuit board, results in sufficient variation in the sizes and geometries of these structures such that securing a compression coupling to the motherboard using these structures may require a significant level of force. By discerning the downward force that is required to overcome the deflection of the housing410in its concave shape405b, an administrator may be guided in applying the correct amount of force in overcoming these manufacturing variances and in securely seating and attaching the compression coupling400to the motherboard. As such, in some embodiments, the prestressed manufacture of the compression coupling housing410may be calibrated to facilitate an administrator using the appropriate amount of force needed to insert a memory module within the coupling400and to uniformly seat the electrical contacts of the coupling400within vias or other structures of a motherboard.

In this manner, embodiments provide a capability by which an administrator may simultaneously install the memory module425in the compression coupling and also attach the compression coupling to electrical contacts provided by the motherboard within an empty memory slot. The force required to straighten the housing410, to shape405a, is supplied by an administrator that inserts a memory module in the coupling400and presses downward until the compression contacts435of the compression coupling become uniformly attached to the motherboard. Once the memory module425has been inserted within the housing410and the compression coupling400has been attached to the motherboard, the memory module may be secured in place using locking arms420a-bthat are rotated until latched within notches along the side edges of the memory module425.

FIG.5is cutaway circuit diagram depicting signaling pathways in memory systems according to embodiments. The illustrated memory system embodiment includes a processor510that utilizes a set of removable memory modules535a-f, such as described with regard toFIG.2. The processor510may be mounted on a printed circuit board505, such as a motherboard of an IHS. The processor510communicates with the removable memory modules535a-fvia traces515that extend within the printed circuit board505from the processor510to the motherboard location where each of the removable memory modules535a-fis coupled to the printed circuit board505. As described, in existing systems, memory sockets are permanently fixed to a printed circuit board. In the illustrated embodiment, however, some or all of the connectors used to attach memory modules535a-fto the motherboard505may use removeable compression couplings, such as those described herein.

As described, memory systems may utilize channels by which multiple memory modules may be accessed concurrently. In the embodiment ofFIG.5, the memory system supports two memory modules per channel (i.e., 2 DPC). As such, inFIG.5, one memory channel is implemented by a trace that extends from the processor510and connects to the first two removable memory modules535aand535b. In the same manner, the second memory channel is implemented by trace that extends from the processor510and connects to the next to removable memory modules535cand535d. As indicated inFIG.5, the first two memory channels are a fully loaded section520of system memory where two memory modules535a-band535c-dare installed in each of the connectors supporting these memory channels. In some embodiments, all of the connectors used in the first section520of system memory be existing connectors that are permanently fixed to the motherboard, such as SMT connectors. Such existing connectors are the most economical type of memory coupling and thus may be utilized in memory slots that are expected to always be occupied, such as those memory slots in the first section520of main memory.

As described, a motherboard may be manufactured to support more memory modules per channel that are actually installed when the motherboard is shipped and installed in an IHS. In embodiments, such underutilization of a memory channel may be supported using the described compression couplings, while eliminating signal stubs in the underutilized memory channels. This particular scenario is illustrated in the second section525, of the illustrated memory system ofFIG.5. In this second section525of system memory, only a single removable memory module is installed in each of the channels. As such, removable memory module535eis the only memory module in its channel, while the other supported slot550aof this channel is left unoccupied. In the same manner, removable memory module535fis the only memory module in its channel, while the other slot550bof this channel is also left unoccupied. Such unoccupied slots550aand55bmay be left empty during manufacture of the printed circuit board505in order to support expansion of the memory capabilities of the memory system. In other instances, memory slots550aand550bmay be unoccupied as a result of system administration that resulted in memory modules being removed from these two slots.

As described, in existing systems where sockets are permanently fixed to a printed circuit board, an unoccupied memory socket results in a stub in the circuit board traces that are used to implement these partially utilized memory channels. As illustrated inFIG.5, such trace portions of a memory channel trace are eliminated through use of the described compression coupling and through the illustrated selection of memory slots in which to utilize the described compression coupling. In some embodiments, all memory modules535a-fthat are illustrated as presently coupled to the memory system may be coupled using memory sockets that are permanently fixed to the motherboard505, such as using existing SMT sockets. Accordingly, in such embodiments, only the two empty memory slots550aand550bare wired for use of the described compression couplings. In other embodiments, any number and combination of memory slots may be wired for use of compression couplings.

The signal stubs that are present in existing systems with unused memory sockets are eliminated in embodiments, however, by choosing the closer of the two memory slots of a particular memory channel to be wired for use of a compression coupling. The memory slot of a memory channel that is further from the processor would be expected to always be in use, such that a permanently fixed memory socket, such as an SMT socket, may be utilized in these memory slots. As illustrated inFIG.5, through selection of the closer memory slots550a-bof the two slots of a memory channel for use of compression couplings, no signal stub is present in the signaling pathways of the underutilize memory channels. More specifically, no signal stub is present in the memory channel trace that connects the processor510to memory module535eand no signal stub is present in the memory channel trace that connects the processor510to memory module535f. Since a memory slot that is wired for use of a compression coupling may remain empty for considerable time, the elimination of such signal stubs may present significant and long-lived improvements in signal integrity within a memory system. In some embodiments, the improved signal integrity may support increased signaling frequencies within the memory channels of the memory system. For example, by eliminating stubs in underutilized memory channels, switching frequencies up to 8.4 GHz may be supported in these 1 DPC memory channels.

Through the described installation process, a compression coupling and a memory module may be simultaneously attached and seated within a memory slot550a,550bof a motherboard that supports use of a compression coupling according to embodiments described herein. As described, the attachment of a compression coupling to the motherboard by an administrator may include the administrator uniformly seating the compression contacts of a compression coupling within electrical contacts provided by the motherboard. Through this coupling of the compression contacts and the contacts provided by the motherboard, the compression coupling may be connected to the memory channel traces, thus fully utilizing the capacity of the memory channel, while eliminating stub traces in these memory channels when the compression coupling is not present.