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Old 03-24-2005, 10:54 PM   #1
Mega Man X
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Angry PSU Fan replacement


Hi!

Once again, I'm having trouble with one of my fans in my desktop PC. Very very strange, it has to be Thursday night (God damn you fans).

Any way, I've to replace my PSU fan. Last night it ran hot and if it was not for some PC beeps, I'd most likely have started a fire . Here are the questions:

1 - Should I buy any 80mm case fan to replace the PSU fan?. Is there any rpm # recommended for specific a 350W PSU? I have one on my case, which runs about 2000 rpms. I guess that's too slow to use on the PSU and it won't blow enough air into the PSU will it?

2 - Strangely, the power supply fan wire is sold on the PSU board. It has two wires: Red and Black. An ordinary 80mm case fan has 3 cords: Red, black and yellow (3 pin). Should I simply cut and sold the red and black on the board ignoring the yellow?

Any help with this would be great. Wish I could keep my PC inside the fridge though .

Regards!

Last edited by Mega Man X; 03-25-2005 at 05:05 AM.
 
Old 03-24-2005, 11:23 PM   #2
rnturn
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My guess is that the yellow lead is some kind of speed control connection. This fan is probably intended to be mounted on the rear of the case and connected to a header on the motherboard. I'm not at all sure what would happen if the yellow lead is not connected. A quick test you could try that doesn't involve butchering the fan leads would be to find a battery of the voltage listed on the fan (probably 12V) and run a couple of wire from the battery terminals to the red and black holes on the fan conector. If the fan spins, then you apparently don't need the yellow connection. A 12V battery isn't a typical size, though, but I'd bet that a 9V transistor radio battery would do well enough for this test. (If you don't have one get one; you can use it in the smoke alarm when you're done.)

Personally, I'd leave the new 80mm fan alone and see if you can find an exact (or darned near exact) replacement at a local Fry's or equivalent electronics house. (It's actually soldered to the PSU electronics board? I've never seen that before but then we're not supposed to be opening the PSUs are we. ). If the case supports the 80mm fan, I'd put it in as a supplement. If you think the original PSU fan got cooked it's probably that there's just too much heat being pushed through the PSE and you need additional cooling for the case anyway.
 
Old 03-24-2005, 11:34 PM   #3
Mega Man X
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Thanks a lot rnturn for your quick reply!

Well, I lifted the PSU Fan seal and dropped a little oil on it. It seems to be spinning again (out loud too). I loved your idea for the test and might try it Thanks! Sadly, every single store is closed today here, so I've to wait till tomorrow or even worse, Tuesday (weekend without my gaming PC, what nightmare ).

I've to stop buying budget stuff, as my PSU too (40 bucks for a nice case and the PSU sounded as a great deal, lol).

Regards!
 
Old 03-25-2005, 10:09 PM   #4
Half_Elf
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I heard somewhere that PSU doesn't really need a fan... if you feel courageous (and have 50$ to spare in case it goes wrong), you could try to just remove the fan and to get off the protective metal case around the PSU... Someone told me a PSU out it's "case" shouldn't overheat... never tried myself
 
Old 03-25-2005, 10:23 PM   #5
J.W.
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Electrical components that overheat have the potential to start a fire. Be sensible.

If you have a fan that is not functioning correctly, my advice would be to remove it and install a suitable replacement. If it's the PSU, you might want to consider replacing the entire unit. About 3 years ago I faced a similar situation, where the PSU fan was running very slow, and the PSU (obviously) was very hot to the touch. I replaced the fan, and all seemed A-OK for about 2 more weeks until the whole system shorted out and I lost the CPU and hard drive as a result. Had I replaced the PSU in the first place, that machine may have still been functioning today.

Who knows, but don't intentionally allow your PC to overheat. That's just plain risky, from several angles. -- J.W.
 
Old 03-25-2005, 10:47 PM   #6
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Most 80mm fans have three wires like mentioned earlier one is +12v (red) one is ground (black) and the yellow is to measure rpms not a speed control. Speed control is done in one of two ways, making pulsating dc voltage or modifying the voltage applied to the fan. According to what you say (the psu running hot) there might be an overload. I would try a different p.s.u. some thing stronger maybe. Another thing i wouldn't try to take the psu out of the case unless (not to replace a fan though) unless you know what you are doing. Also something else people may not know (speaking from personal experience a psu can cause problems anywhere and of any sort. There are at least two explanations i can think of: the psu might not be offering enough power to certain components, it might be giving an unstable power. Also if there is an overload on one the lines of the psu it can affect the other lines, one way is by stepping up the voltage causing hard drives to heat like crazy. By the way that is not a good thing!!! Of course, my recommendation is still to try a different psu.
 
Old 03-25-2005, 11:46 PM   #7
rnturn
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Quote:
Originally posted by Xerop
Most 80mm fans have three wires like mentioned earlier one is +12s- (red) one is ground (black) and the yellow is to measure rpms not a speed control. ... Of course, my recommendation is still to try a different psu.
Ah. Thanks for the info on that yellow lead.

I agree about replacing the PSU. Especially when the balky fan is soldered to the electronics board. Desoldering the old fan, if not done right, could leave a little bit of solder floating around and could cause a short and could take major components of the system out. It's not worth the risk when a nice 400W ATX/P4-ready PSU can be had for under +ACQ-40. I'd still add the 80mm fan to the case to reduce the amount of heat being passed through the PSU and its fan. PSU component (heck, most any electronics) lifetime will be shortened if it's operating for long periods when the ambient temperature is high.
 
Old 03-28-2005, 02:20 PM   #8
Mega Man X
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Hey guys, thanks for the replies . I've been a bit busy installing gentoo the past days and totally forgot about this thread.

Well, just clarifying: I don't think this power supply would survive without a fan. The fan was just running slow (very slow) and the thing overheat the hell out of it, making the computer crash (but not shutdown, which is most disturbing) and smell like crappy . Wasn't I near the PC, could I've lost the entire machine, which is not even a month old yet (ouch).

The fan seems to be running alright now since my oil-drop-workaround. No overheats and the computer runs quite silently.

I will try to replace the PSU (if necessary) when I get my next payment, in about another month .

I will also make sure to buy a fire extinguish and place near my PC's, just in case

Regards!

Last edited by Mega Man X; 03-28-2005 at 02:21 PM.
 
Old 04-03-2005, 05:13 PM   #9
spineboy
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POwer supply and fans

I routinely switch out fans from most power supplies I get and put in Panaflo 80mm fans - VERY quiet (29 dB) and moves a good amout of air too. Another option would be too just buy a Seasonic power supply -tthey are some of the quietest power supplies on the market (see silent computing website - just google it) and they are MUCH more efficient than most power supplies. Electricity cost savings will pay for the PS in less than a year if your computer is on most of the day. I pretty much only use Seasonoc power supplies in all my boxes now, and have noticed a drop in the monthly electric bill.
 
Old 04-04-2005, 02:05 AM   #10
Thorium
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I'd be scared to open up a psu...that capacitor is "big" :P
 
  


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