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PSU fan/mobo

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August 26, 2010 10:28:29 PM

Ok, so I just got done building my new mid range gaming system and it's been trouble from the start. I connected everything etc, and hit power and nothing. The led on my fan came on for maybe half a second and that was it. So first I tested the psu thinking that would be the likely cause and easiest to test, but nope all readings in the green. Next I checked and made sure everything was seated correctly and firmly. Still no powering up. Then I shorted the power switch to see if that was it, but alas no change. So then I unplugged everything uneeded (gpu, case fans, hdd, optical drive etc) and hooked up one by one while trying to power on.

It powered up when everything was taken out. Put in gpu, still powered up, hooked hdd up, still turned on. On down the line, till I got to the PSU fan. When I hook the power supply's fan up, nothing. It refuses to turn on. Now, I can leave this unhooked and everything runs fine, I am hesitant to do this and use it on a regular basis though.

So then 2 questions. My mobo has a 3 pin connector for the psu fan, my psu has a 4 pin connector. I know that the two can work together and I followed several guides on which way they should be hooked up, but to no avail (really there are only two possibilities to hook it up, either use the left 3 holes on the 4 pin connector, or the right 3) Could this be a problem with my mobo, psu, and is there any way around this?

2nd question.
If no way around this, estimates on how dangerous running a psu without a fan would be? The psu fan isn't designed well, it points down instead of out. So it basically draws heat out of the psu and pushes it straight down in the tower, of course to fix this there is a 120mm fan in the back that pulls that air out. Two 120mm fans on the side cover as well pulling air in, then 120mm fan on the front pulling air in as well. Basically should I even worry about the psu's fan not working if there is no fix available?

More about : psu fan mobo

August 26, 2010 10:45:42 PM

Do you mean CPU fan? There is nothing on the motherboard that should plug into a PSU fan.

Try plugging a case fan in the CPU FAN power plug long enough to see if that works (dont let the CPU temp go up too much). If it does, RMA the CPU cooler or move the case fan to the CPU cooler. If it doesnt the problem could be in the motherboard.

I think there 3-4pin fan adapters that you might get cheap at frys or radio shack. That might work also.
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August 27, 2010 5:33:39 AM

How did you test the PSU?

rekindledflame said:

So then 2 questions. My mobo has a 3 pin connector for the psu fan, my psu has a 4 pin connector.

What kind of motherboard? What kind of PSU? For that matter, what are all your system specs?
Does the 4 pin connector look like the one pictured on the top row on the right of:
http://www.playtool.com/pages/psuconnectors/connectors....

rekindledflame said:

2nd question.
If no way around this, estimates on how dangerous running a psu without a fan would be? The psu fan isn't designed well, it points down instead of out.

Go to newegg and look at the pictures of the PSU. Most do have a bottom mounted fan.

rekindledflame said:

So it basically draws heat out of the psu and pushes it straight down in the tower, of course to fix this there is a 120mm fan in the back that pulls that air out.

No it doesn't. The fan pulls air from inside the case and exhausts it through the PSU and out the back.
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