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CPU fan not working properly after power loss.

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December 20, 2010 4:56:02 PM

Hi guys,

So this morning my dad was in my room taking some old furniture out, and he unplugged my power bar from the wall while all of my equipment was on. Needless to say I was a little upset with him. Now, as I was afraid of, my computer is not starting up. I've opened it up and it looks as though my GPU fans are spinning fine. My system fans, however, do not spin. And my CPU fan IS spinning, but its behaving strangely. It can't seem to get going very fast, and it sounds like its trying every few seconds but fails. I've noticed when I power on the machine as well, that I can hear faint 'cracking' noises. Now, I don't have much experience in the way of dealing with the innards of my computer, but I'm thinking that's caused by the CPU not being cooled properly? Other noteworthy information: I do not have any kind of signal being sent to my monitor. ALSO, I just tried starting it again to see if there were any other abnormalities, and now the CPU fan took a few seconds to even start up and barely got going at all.

Obviously something is buggered, and is going to have to be replaced. I'm really hoping that it's the Power Supply, and that I don't have to have a new machine built because of a ruined motherboard.

Opinions on what likely needs replacing?
Thanks alot in advance!
a c 123 à CPUs
December 20, 2010 6:11:58 PM

What would help a lot is your system specs.

But from the info you have given I do have an idea. It seems to me that your PSU has probably bit the dust. The cracling noise could be capacitors in it dying. Considering that what you had was a instant drop in voltage and most PSUs don't come with protection for that, I would guess that.

To rule out that the mobo is dead though, I would look at all the capacitors on it:



Normal capacitors look and feel flat on top. Bad capacitors look like they are bulging or they will even have some yellowish brown stuff coming out of them. The thing is, capacitors help to regulate the voltage to components on the mobo so if they are going bad it would cause the CPU fan not to work since it connects to the mobo.

BUT, since you say the system fans are not spinning (I would assume you mean case fans) then that is why I will lean towards the PSU being bad since case fans are directly tied into the PSU.

Try a second PSU if you have it or if you have a PSU tester, test it.
December 20, 2010 6:29:49 PM

Sadly, my old roommate built this machine a few years back and I'm not completely familiar with all the hardware that's in it, and since I can't get it started to look at the information given by Windows, all I can tell you is that it was a high-end gaming computer at the time. It has 2 nVidia 8800GTs, 4GB RAM, an Asus P5N-E SLI motherboard and the PSU is an OCZ Technology GameXstream 700W, which is going to cost me around $100 to replace with an equivalent if I need to.

I took a look at the capacitors and they all look alright to me. The old roommate suggested i try removing the CMOS battery for a bit, which didn't have an effect. I don't have an extra PSU or a tester. Is a tester relatively simple to use and easy to find?

Edit: I did mean case fans, yes. And thanks a lot for the help so far. I appreciate it :) 
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a b à CPUs
December 20, 2010 6:36:40 PM

Have you tried the old faithfull, unplug everything from the board and the psu.

Press the power button on your case a few times then plug just what you need back in to boot.

Simple but sometimes effective.

Do you have access to another machine that you could try your psu on?
December 20, 2010 6:45:08 PM

beanoslim said:
Have you tried the old faithfull, unplug everything from the board and the psu.

Press the power button on your case a few times then plug just what you need back in to boot.

Simple but sometimes effective.

Do you have access to another machine that you could try your psu on?


Since I'm not the most familiar with tinkering inside a computer, I try to stay away from taking everything apart. The few times I have switched out hardware, I always end up coming to the forums because I've knocked a cable loose or done something else stupid and can't tell what it is. I've even managed to put RAM in backwards once. I'll do what I have to, as a learning experience, but taking it all apart might be a little much for me right now :p 

It's for the above reason that I'd rather not try my PSU in my dad's machine either. If I make a mistake on mine, I'm okay with that. I don't want to mess up anything on his. I should thank the roommate that built my machine, though. He kept everything well organized, so it's easier on me when I'm looking around inside of it.

Interesting Quirk: As mentioned before, the system doesn't even appear to be powering on any more. I've noticed now, though, that if I press the power button on the front, then switch the power off at the back after a few seconds, the case fans will suddenly spin for a moment.
a c 123 à CPUs
December 20, 2010 7:24:07 PM

snakesoldier said:
Sadly, my old roommate built this machine a few years back and I'm not completely familiar with all the hardware that's in it, and since I can't get it started to look at the information given by Windows, all I can tell you is that it was a high-end gaming computer at the time. It has 2 nVidia 8800GTs, 4GB RAM, an Asus P5N-E SLI motherboard and the PSU is an OCZ Technology GameXstream 700W, which is going to cost me around $100 to replace with an equivalent if I need to.

I took a look at the capacitors and they all look alright to me. The old roommate suggested i try removing the CMOS battery for a bit, which didn't have an effect. I don't have an extra PSU or a tester. Is a tester relatively simple to use and easy to find?

Edit: I did mean case fans, yes. And thanks a lot for the help so far. I appreciate it :) 


Well you will ned at least a decent 600W PSU that can provide enough watts on the 12V rail for the dual GPUs but if you can I would get either a Corsair or a Thermltake PSU. They have some of the best ratings of all PSUs. My 800W BFG PSU died recently and I went and bought a TX850W Corsair PSU. It has undervoltage and overvoltage protection along with a single 12V rail that has massive power going to it. It died in kind of the same way yours did. We had a brown out and my PC turned off and wouldn't turn back on. Put in my new Corsair and it lit up all blue like normal. Strange thing is my wifes PC (one of my old machines) didn't even turn off. It stayed on and the PSU survived.

If the capacitors look fine (you can also test by touching the top) then the mobo is most likely not the problem also adding in that you confirmed they are case fans that wont spin adds to the PSU being dead.

As for testers, they are simple to use and I had one like this at work:

http://www.google.com/products/catalog?hl=en&q=PSU+test...

You have to unplug the PC from the wall then unplug the 24 pin power connector and the extra 4 pin power connector. Then plug them into the tester (its hard to mess up since they have different shapes) and plug the PSU back into the wall and flip the on/off switch in the back of the PSU (if it has one, which I am pretty sure OCZ does) and look at the screen on the tester. If it beeps once then its fine but I like to give it 5 minutes to make sure. There will be 3 voltages (well 6 but still). +/- 12v, +/- 5V and +/- 3.3V (+/- means positive and negative voltages). You want them to be as close to their voltage as possible. So 12.1V is fine but 12.5V or 11.5V is bad.

One down side to the PSU tester though, it doesn't test the current. So the voltage could be good but the current could be bad. I don't think you need a tester but you can get one if you want to be 100% positive or see if your friend has one.

I still say PSU and I would get this one:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

But thats just my opinion.
a b à CPUs
December 20, 2010 7:29:46 PM

I just mean unplugging all your psu cables, not removing anything, just on occasions I have found that draining the system of power can sometimes help.

With your last comment it is pointing to psu failure but I would still try my unplugging suggestion.

A new psu won't cost you $100 either, from what system you have listed you probably don't need more than 500w.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

What is this rebate thing? http://www.newegg.com/Product/Product.aspx?Item=N82E168...
December 20, 2010 7:59:02 PM

I'm headed out to work for the day, but I'll give that unplugging trick a try and take a look at the links you guys gave me when I get home. At least I know that the PSU is very likely the culprit, now. I'm much less stressed than I was a few hours ago. Thanks a lot for the help, both of you. It's greatly appreciated.
!