replacing the fan from a PSU

Chaps,

I have this wonderful OCZ 520W PSU which for the most part is great - however, the fan while being relatively quiet, stands at 44dB on full load which i feel could be replaced by a fan that could do a better job.

I don't think the CMF is awfully high but have a couple of questions...

Does the replacement fan have to be attached to the psu or can it be attached to the motherboard?

If not, are there cables to convert the 3 pin to a tiny one that will connect to the PSU?

Any replies appreciated!

Some fans like the Antec Tri cool come with a molex connector (same as on IDE drives) or you can get a molex to 3 pin adaptor check the scan site.

PSUs normally cvontrol their own fan (which makes sense - it is the source of heat - so it 'knows' what cooling needs to be applied.

Replacing the fan with one of equivalent size should be straightforward, however if the fan you are replacing has a 3 pin connector (so it provides feedback as to how fast it is rotating) then you should replace it with the same type.

If it is a two pin standard fan, then replacement will be easier, but it should still be connected back to the fan controller (if any) in the PSU. You could run it flat out by connecting it to one of the 12v outputs of the PSU - but that would probably be noisier - and there is the possibility that if the PSU doesn't detect a fan, it will shut itself down. (Diito if the fan controller is expecting a 3 pin fan with rotational feedback - but doesn't detect that feedback)

Hard to be specific without seeing a cct diagram - but those are the obvious options.

The only thing to keep in mind is that you invalidate the warrenty when you do this. This can become important if you fit a fan that's incapable of keeping the PSU cool, as some low noise ones just aren't up to the task.

Additionally, before you fiddle around in the PSU, let it rest for a day to discharge the capacitors - that's what the grapevine whispered.

Quote:

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Originally Posted by Cistron

Additionally, before you fiddle around in the PSU, let it rest for a day to discharge the capacitors - that's what the grapevine whispered.

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When you power down, the capacitors discharge pretty quickly - and there should be bleed resistors across any high voltage ones. So while leaving it for a day won't do any harm, it really isn't necessary - particularly if it isn't powered up off load (when there is nothing to discharge any stored energy)

Once the mobo LED extinguishes, it will be safe - particularly by the time you have dismantled everything ang got it out of the case.

From opening up a few PSUs I can tell you it will depend a lot on the PSU and you'll only know when you open it.
Some use 2 pin fans some use 3 pin some have the wires directly solidered onto the pcb.
All of the 3 pin and 2 pin I've come across so far a standard connectors (I've talen old psu's apart to pinch the fans ;) )
The 2pin ones are the same basic connector but with only a 2 pin socket instead of 3 (you can fit thoes on to a 3pin header but cutting off one lug) You can remove the wires and attached contact from the connector quite eaisly.

However keep inmind that opening up the psu invalidates the warranty, most have a sticker on the case that you have to break, so if it dies you cannot claim you didn't open it.
Also any pokeing around is done at your own risk if you break it and it takes the rest of your pc with it you've only your self to blame (and this is the reason most people don't poke around in side them.)

make sure you unplug it first.. or someone may end up in quite a nasty state :P

but on a more serious note, you will definately invalidate the warranty on your PSU by doing this, so it's at your own risk mate..

but i'm pretty sure if you get a decent enough fan and have some sense of what you're doing, then i'm pretty sure you won't damage the circuitry/workings of your PSU.. but tbh, i wouldn't like to risk it..

44dB seems very loud though.. especially for a PSU from such a respectable and well known brand.

So what you guys are saying is that i should cut of the 3 pin and put a 2 pin on the end of the new fan to connect inside of the psu and not the motherboard?

Short answer... Yes
Long answer... yes - connect the fan using the correct connection to the PSU - not the mobo. (if the fan you are replacing is a two wire, and you are replacing it with a three wire, make sure you don't connect the speed monitoring connection to anything)