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PC wont post, CPU fan not spinning

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December 1, 2010 12:57:24 PM

I'm sorry for my English, I'm 13 now and just had 1 year of English @ school.. If you're dutch, this is my topic on a dutch tech site:
http://gathering.tweakers.net/forum/list_messages/1436689/last

Hello,

new to the forums, I hope you can help me out with this one:

My specs are(check the signature):

i5 750 @ 3,6 Ghz 1.235V
GA P55M-UD2 F11
4 GB OCZ Gold @ 1440 Mhz 1.560V
CM Hyper TX3, temps are okay(@1.235V 56C max)
Asus EAH4890 stock BIOS
Antec 300
No optical drives, just a SATA HDD: WD 640 GB SATA
ToPower SilentEZ 500W: I guess this is the problem, more info:

12V1=20A, 12V2=23A, together they're outputting 384W, which isn't right, cuz 43x12 is 516, a lot of HW sites said this PSU was undervolted @ the 12V rail, and HWMonitor says so too(3.31V max during stresstests). It will stay stable during Prime95, Furmark and (forgot the name) a memory stresser which works in Windows(of course you cant test mem that's being used then, but I also did the mem test of Windows twice).

But the problem is: CPU fan will stop spinning after 1/10th of a second. It just stops and wont output any video(also tested a HD2400 PCI which works in any other PC). I guess this is because it's overheating without the fan on, or the mobo will block it. When I put another fan(stock 72MM one from AMD)on the 4 pin PWM it won't post/boot either, even if its working as a intake to the cooling ribs, so it shouldn't overheat, i guess the max temp with a incorrectly placed and cheap fan would be 60C during boot. But it won't boot, multiple fans tried, CMOS cleared, different GPU, etc.

But i think the mobo is blocking the fan, because it will spin in the beginning, but after a couple of millisecond it'll just stop, all other casefans/light/mobo-lights/gpu-lights are burning as they should. I dont have a speaker which I can attacht to the MB to check the sounds its making. The problem happened this way:

Playing Black Ops MP

Weird IEEEEEEEEEEE sound from the speakers, wasn't stopping after 1 minute, ctrl/alt/delete wasn't working. I was stupid enough not to open the case, but I thought it was just a DX9 crash or another small problem.

Shut the PC down after a minute.

I pressed the power button again to power it on(reset button's not attached), but there wasn't anything showing up on my screen.

Shut it down again, opened the case to see if there was something on fire/ broken, Im glad I couldn't find anything.

Booted it up again, i saw the fan spinning up and stopping directly after that. shut it down quickly to prevent the CPU from frying.

Cleared the CMOS, didn't help

Another fan tried, the fan worked, but it wasn't booting or even posting yet.

Another GPU tried, still no spinning CPU fan or post.

Posted this on a Dutch forum first, now this one, cuz when I Google people always post their problems here, and there are always some guys with good reply's. Tnx already, hoping the best :bounce: 
December 1, 2010 2:19:35 PM

Just made a test bench, still didn't work.... My dad should come home with another 92MM fan in a couple of minutes, ill keep ya updated(If you wanna be updated... Not a single reply! Threads created after mine already have 10 reply's! Guess my problem isnt that interresting...
a b B Homebuilt system
December 1, 2010 3:29:14 PM

The fan "twitch" could be a sign of a short somewhere in the cabling or on the motherboard. Has this system every posted / booted? Keep the troubleshooting simple... Start pulling components and, if needed, try booting with the MB out of the case (be careful of static / grounding). Also ensure the 8-pin CPU power connector on the MB is connected.
a b B Homebuilt system
December 1, 2010 7:28:34 PM

To add to what sadams04 mentioned, also work through our troubleshooting guide, it was designed to help people with "no boot" and "no display" problems. Click on the link in my signature and make sure you work through every applicable step, even if it sounds redundant; double checking is always a good idea.
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