PC Temperature Contol. - Page 1
Forum section: electronics / projects

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 01, 2013, 12:52:15 pm
content: As you can see the last week i went crazy with my computer (i formated it ... then fixed the ram problem, then i setup the network sharing , overcklocked the cpu (with not great effects but it worked better) , and now i have a problem with the pc temperature)and now the temperature rose..... literally.My motherboard is an Gigabyte GA-P55M-UD2 and it has only one fan slot (which i used to connect a 120mm 12 volt fan)but nothing else...What can i do to just put more fans in the PC (i dont need to control the temperature in all of them)Also why BIOS dont see the fan ... even Speedfan wont recognise the fan...Let me know what to do please i have 2 more fans and i can order more to cool my pc down (but i dont think ill need more than 2)I have also thought of slipping a wire inside the pc or using the 12 volt rail from my power supply

author: madires
author_rank: Super Contributor
timestamp: May 01, 2013, 01:17:24 pm
content: Does your current fan has two, three or four wires? Two wires are just power, the three wire version adds a sense wire for the mainboard for the RPM feedback and the four wire version is used for a PWM driven fan. Since the BIOS or fan tool don't show any RPM I assume that you got a simple two wire fan. If the additional fans are two wire also simply power them by the 12V rail (use a free Molex for disks, cheap adapters are available).

author: Jon86
author_rank: Frequent Contributor
timestamp: May 01, 2013, 02:37:15 pm
content: I hope you're not overclocking the CPU with the stock cooler

author: mariush
author_rank: Super Contributor
timestamp: May 01, 2013, 03:10:28 pm
content: The motherboard only has two fan headers: CPU_FAN and SYS_FANBoth have 4 pins but you can plug any type of fan on those 4 pin connectors.Fans can have 2, 3 or 4 wires: black is ground, red is 12v , next wire is rpm speed sensor , next wire is pulse width modulationThe first two wires are power going to the fanThe third wire called rpm senson is sending a signal to the motherboard telling it the speed the fan spins at and can be optional (in which case the motherboard always says 0 rotations per minute)The fourth wire is pwm and is present only if the fan is of that type - the motherboard sends a signal through this wire to the fan telling it to adjust the speed.All fans with 2 or 3 wires can be plugged in a connector on the motherboard that has 4 pins (you just leave the 4th pin unused). In this case the motherboard can't adjust the speed, it can only read the rotation if the fan has 3 wires.Most fans with 4 wires can be used in a connector on the motherboard that has only 2 or 3 pins, but they'll always run at full speed. Some fans with 4 wires require that 4th pin (the pwm connection).You don't need to plug fans on the motherboard through. You can get any fan with 2 or 3 wires, cut out that tiny connector, and connect the black and red wires to the power supply. Black goes to Black on a molex (hdd connector), red wire goes to yellow (12v) on the hdd connector.So conclusion : you can control the speed of a fan using software on your pc only if that fan has 4 wires.You may not see the second fan on your pc because the software you use is stupid. Use something else, for example Aida64 (google it)You can make regular 2-3 wire fans adjust their speed quite easily, with components you can buy on eBay or other electronics store.The easiest way to adjust speed is using resistors to limit the current going to the fan, that's how those fans that have a switch on the cable with low/medium/high speed presets work. You have the formula V = I x R which gives you I = V / R or R = V /IYou have on the fan the current it uses, let's say 12v at 0.2 A so if you want it to run at 8v 0.2A (making it about 70% speed) then the resistor needs to drop 12v-8v = 4v so that the fan will only see 8v.... so you do the math : R = 4 / 0.2 = 20 ohm which is an odd value but you can easily find 22-24 ohm resistors. The power dissipated in the resistor is then P = R x I x I = 20x0.2x0.2 = 0.8 watts so you need a resistor that's rated for at least 1wThe other way would be to make your own voltage control for the fan, using a simple voltage regulatorR2 can be a linear potentiometer of 1 kOhm , at about 360 ohm the fan will run at very low speed or may not run at all (5v) and at 1000 ohm (the max on the potentiometer) you'll get maybe 11.5v which is almost the full speed.1117 is a very generic chip, you can find it made by lots of companies, just search for 1117 adjustable .. LD1117-ADJ, LM1117-ADJ etc .. for example here's a 10pack on ebay :http://www.ebay.com/itm/10pcs-LM1117T-ADJ-LM1117T-LD1117-ADJ-TO-220-/280945323661?pt=LH_DefaultDomain_0&hash=item4169a56e8dpotentiometers are also cheap :http://www.ebay.com/sch/i.html?_odkw=potentiometer+1+kohm&_sop=15&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0&_nkw=potentiometer+1kohm&_sacat=0

author: Jon86
author_rank: Frequent Contributor
timestamp: May 01, 2013, 03:35:56 pm
content: Quote from: mariush on May 01, 2013, 03:10:28 pmThis isn't true. Even two or three pin fans can be software controlled if the motherboard has the capability, which most do.Also, just adding loads of case fans probably won't help much with temps.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 01, 2013, 09:44:13 pm
content: Quote from: madires on May 01, 2013, 01:17:24 pmIts a 3 wire fan and ... whats the thing i can do with molex connectors?

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 01, 2013, 09:44:44 pm
content: Quote from: Jon86 on May 01, 2013, 02:37:15 pmWell crap.... ill reset it now ....

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 01, 2013, 09:48:37 pm
content: Quote from: mariush on May 01, 2013, 03:10:28 pmThanks good advise.But i think that a LM317 circuit will do the job.Also i can pick one 12 volt 1 amp power supply only for powering the fans... so i can hook up as many fans i want.

author: Jon86
author_rank: Frequent Contributor
timestamp: May 01, 2013, 09:53:22 pm
content: Quote from: ChrisGreece52 on May 01, 2013, 09:44:44 pmGood ideaThe stock cooler is only designed to dissipate the power of the processor at its default clock.That's probably why your temps are high.

author: mariush
author_rank: Super Contributor
timestamp: May 02, 2013, 12:10:55 am
content: Quote from: ChrisGreece52 on May 01, 2013, 09:48:37 pmThe power supply in your computer already has about 30-50A of power on 12v. There's no point in getting a separate power supply for the fans, it would be just stupid to spend money on separate 12v power supply when you have perfectly good one inside the pc.LM317 has a voltage drop of about 2v at 1A, about 1.8v at 200-500mA. So at best, your fan is going to see 12v - 2v = 10v. It only gives you a peak of 1.5A but basically if you adjust the voltage, you adjust the voltage of all fans connected to it, so you probably don't want to connect all fans to one potentiometer.LD1117/LM1117 has a 1v voltage drop, so it allows you to run the fan at higher voltage (11v and higher) and also dissipates less watts as heat (basically about half the wasted power of a lm317). So with just 1 fan, you don't really get it hot enough to need a heatsink. A LM317 will need at least a small heatsink.1117 only has a guaranteed 0.8A output but normally it can do 950-1000mA just fine... but either way, it doesn't matter, like I said you probably won't put several fans on a single regulator.

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 02, 2013, 11:35:32 am
content: Quote from: Jon86 on May 01, 2013, 09:53:22 pmI did set the clock to the default state but the graphics card temp is still pretty high

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 02, 2013, 11:37:25 am
content: Quote from: mariush on May 02, 2013, 12:10:55 amGot it so i only have to get LD117 and build a circuit.

author: madires
author_rank: Super Contributor
timestamp: May 02, 2013, 12:07:09 pm
content: Quote from: ChrisGreece52 on May 01, 2013, 09:44:13 pmIt's the old standard power connector for disk drives like HDDs or optical disks (Gnd, +5V & +12V). Instead of plugging one into a HDD simply use a adapter (Molex to 2-Pin fan) to power the additional fan or fan control. BTW, there are tons of 12V fan control circuits to be found in the internet. A nice and small project :-)

author: ChrisGreece52
author_rank: Frequent Contributor
timestamp: May 02, 2013, 12:29:59 pm
content: Thank you for the information.I felt such an idiot because i knew what molex connectors was but i could not match it with the work "molex" for some reason ... again thank you also i have made an lm317 cicruit for controling led brightness and other stuff but i did it to kill time

author: SeanB
author_rank: Super Contributor
timestamp: May 02, 2013, 03:51:36 pm
content: No need for a complex speed controller, all you need is a 470R variable resistor across the supply and connect the wiper to a TIP31 transistor base, collector to 12V and emitter to the fans. Adjustable from 0-11V then, and capable of around 1A at max output. Will need a small heatsink on the transistor to dissipate heat.

author: Jon86
author_rank: Frequent Contributor
timestamp: May 02, 2013, 03:59:32 pm
content: Linear voltage regulation probably isn't the best idea. You can't control the fan very well and it dissipates a lot of heat in whatever you're controlling it with, but if that's all you want to bother with then it'll do.Bear in mind that you can get a proper PWM fan controller that can control multiple fans online pretty cheap.