Need comments on PSU modification.

Jognt · Aug 30, 2008

Hi there

Im using a Coolermaster iGreen 500w PSU that is just about completely silent!

For the first minute i turn on my PC...

As soon as the PSU/PC components warm up, the fan starts to turn faster, producing a very very very annoying whine/wine.

Recently i cleaned it, didn't help, i can hear it above all of my fans! (1800RPM 120mm's)

The actual mod im planning:
There is already a 120mm fan blowing upwards, but i'm planning to add another ~80mm fan (probably ~1800RPM), which will blow air towards the back of the case.
I'm hoping this helps the air out of the PSU, and cools it down enough to give me some well-earned sleep at night!

Has anyone got any experience with this?
This things i'm thinking of are:
- Will it work at all?
- Will the turbulence caused by two streams of air simply worsen cooling performance?
- Will it be hazardous for the extra fan if i connect it to the same power supply points as the 120mm main fan? Or is this fine?

So, what do you think?

Adragontattoo · Aug 30, 2008

Does it NEED the 80mm? Could you use a 92 instead?

Push pull config might help, though you would need a second fan that is at least equal to the intake.

Jognt · Aug 31, 2008

Adragontattoo said:
Does it NEED the 80mm? Could you use a 92 instead?

Push pull config might help, though you would need a second fan that is at least equal to the intake.

The fan size isn't written in stone yet, im just planning to fit the biggest fan i can fit on the side

By push-pull, do you mean getting rid of the 120mm all together and just putting a fan in the front and rear of the psu?

I've drawn a picture in paint to illustrate my idea.

To add another point to what im thinking about:
- Will i kill a fan if i connect the extra fan to the same power cables?

mepis · Aug 31, 2008

The idea you have would work to cool the PSU by the diagram above. Have you considered oiling the bearings in the fan though? Or is it a whine and hiss from the air moving through the fan itself? If it's the bearings you could clean the fan again and drill a small hole in the fan bearing casing and squirt some rem oil in there. Rem oil will make it very quiet and it's safe for electronics. You can go to walmart and pick some up in the sporting goods section for a little over $3. It's meant for gun cleaning and lubrication but it's as versatile as 3-in-1 oil.

Jognt · Aug 31, 2008

mepis said:
The idea you have would work to cool the PSU by the diagram above. Have you considered oiling the bearings in the fan though? Or is it a whine and hiss from the air moving through the fan itself? If it's the bearings you could clean the fan again and drill a small hole in the fan bearing casing and squirt some rem oil in there. Rem oil will make it very quiet and it's safe for electronics. You can go to walmart and pick some up in the sporting goods section for a little over $3. It's meant for gun cleaning and lubrication but it's as versatile as 3-in-1 oil.

I'm not really sure if the bearings are the problem. I'm not sure what kind of sound it is either..

It's not a mechanical rattle as you get with old/dead fans, and it's not the whooshing sound you get from airflow.
It's a strange buzz coming from it, and when the fan spins faster, the buzz gets higher in pitch..

It has always made this much noise, but i started noticing a lot more when i replaced my 2400RPM fans with 1800RPM ones

I've also been thinking about replacing the 120mm all together, and just use a different fan (got a silverstone 2400RPM 120mm lying around here, 9 bladed one.) But i don't know the specs of the stock CM fan.. (12v 0.5A?)

Argh, just thought it could also be the sound of air moving through the grill in the back, or moving against the parts in the PSU, instead of a lousy fan.
Not sure about anything anymore xD

mepis · Aug 31, 2008

It could very well be the sound being pushed through the grill in the back. Small tight closed grills with fans behind them do make that noise. Instead of hacking apart your pus and adding another fan I would use your trusty old dremel and cut away the grill in the back. Grease your bearings to as that wont hurt and youll have the fan out of it anyway cutting the grill off. I imagine that would take away all the noise. If it's always made that sound then chances are it's the tight grill in the back. You could always record the noise and we would be able to help identify it.

Also if your not sure of the power of the fan that's there to replace it with a silverstone I really wouldnt splice another fan into the same connection. I dont think it would work for your concept anyway because the control wire on the fans measure and change resistance value if I remember right (it's been years since I looked) and splicing another fan in would change those values.

Jognt · Sep 3, 2008

mepis said:
It could very well be the sound being pushed through the grill in the back. Small tight closed grills with fans behind them do make that noise. Instead of hacking apart your pus and adding another fan I would use your trusty old dremel and cut away the grill in the back. Grease your bearings to as that wont hurt and youll have the fan out of it anyway cutting the grill off. I imagine that would take away all the noise. If it's always made that sound then chances are it's the tight grill in the back. You could always record the noise and we would be able to help identify it.

Also if your not sure of the power of the fan that's there to replace it with a silverstone I really wouldnt splice another fan into the same connection. I dont think it would work for your concept anyway because the control wire on the fans measure and change resistance value if I remember right (it's been years since I looked) and splicing another fan in would change those values.

Okay, so splicing the extra fan on there is a bad idea. okay

It's not like it has one of those extremely restrictive grills, the rear looks like this:
http://www.hal-pc.org/journal/2007/07_june/images/0607PowerSupply.jpg

So that should be enough space.

I recorded the sound with my phone, which means it's a .AMR file. I don't know if you can open it, but quicktime can open it on my mac

The volume is very low, so you have to turn up the volume to be able to hear it.

What you hear are two things, the air whooshing, and a mechanical whine behind that.

It's the whine that annoys me, since i can hear that in another room

Added zipped .amr file. let me know if you can't open it.

mepis · Sep 3, 2008

I couldnt open the AMR file. Im in nix and to be honest Im kinda feeling way lazy at the moment and the codec isnt readily available. Anyway the whooshing could happen from a grill with tiny things like that. I still say grease the bearings. The grease could just be drying and causing the whining.

kayson · Sep 3, 2008

Just don't kill yourself.

Automiketic · Sep 3, 2008

this may sound dumb but when u turn the comp off and look at the fan do any of the blades have a mark on them or knicks? is there a cricle all the way around the fan on the blades? maybe the fan is slightly rubbing something. i would suspect grill, it could have been easily bent in transport. sounds dumb but could be a simple solution. as far as the fan on the back of the psu, i have done it before and it helped a ton, but mine had the fan one the very back of the psu not the bottom and i just connected it through a regular molex instead of inside the psu. hope this helps and good luck!

Need comments on PSU modification.

Jognt

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