How to slow down the PSU fan?

PSUs: The source of DC power for all components in the PC & often a big noise source.

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soundOFsilence
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How to slow down the PSU fan?

Post by soundOFsilence » Fri Dec 12, 2003 9:10 am

I have a workspower 360W 120mm PSU (www.workspower.com), even though it has a 120mm fan it is very noisy as it does not have fan speed control (neither manual not automatic) based on load or temparature. It just keeps spinning on max speed (or so it seems) and does not vary spin rate or noise.

What is the best way to slow that fan down? Can I use a Zalman fanmate? I searched the posts here and read the guide for adding a thermistor, neither really answered my question. What voltage would that fan carry? Would I need to do soldering? (havent done that for years now and dont have the gun)

I have a p4p800 deluxe, and it has PSU fan monitoring I think, does that help in any way?

Or do I have to get my credit card and buy a quiet PSU?

Thanks in advance!
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dukla2000
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Re: How to slow down the PSU fan?

Post by dukla2000 » Fri Dec 12, 2003 1:16 pm

soundOFsilence wrote:Or do I have to get my credit card and buy a quiet PSU?
Well if you used to have a licence to drive a soldering iron, it is probably more fun to try break the workspower first :lol:
soundOFsilence wrote:What is the best way to slow that fan down? Can I use a Zalman fanmate? I searched the posts here and read the guide for adding a thermistor, neither really answered my question. What voltage would that fan carry?
A number of options up to and including replacing the fan. A Zalman fanmate is a handy way to vary the fan speed, or a fixed resistor or ... To start with your last question: it is a 12V DC fan. You dont necessarily have to solder, but very likely you will have to join some wires so block connectors or plain "twist them together and a wrap of insulation tape" may do.

Difficulty is fitting any speed variation (eg fanmate) inside the psu itself. Which means you may want to unplug (or cut) the fan leads inside the psu and take them out of the psu together with all the other cables. Then if you are lucky and the fan had a plug you can connect up a fanmate. If you had to cut the fan wires you will need to get a connector onto the fan so it will fit the fanmate.

However finding those connectors (if you dont have 1 you can borrow from a spare fan) is hard work (probably easier to buy the cheapest fan at your local PC shop just for the connector). Then again, if you dont have the fanmate yet it may be simpler to 5V or 7V the fan directly - see this guide.

However, before you slow/quiet the psu fan too much, make sure you will still have adequate case ventilation afterwards. If that psu fan is your only case ventilation and you slow it significantly, your case temps could rise higher than you are happy with.

larrymoencurly
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Post by larrymoencurly » Fri Dec 12, 2003 3:19 pm

Wire a 50 ohm thermistor in series with the fan's red lead and silicone seal the thermistor on the low voltage heatsink (the one closest to all the wires coming out of the PSU and farthest from the big cylindrical capacitor(s) )?

soundOFsilence
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Post by soundOFsilence » Sun Dec 14, 2003 2:49 am

I just did the 5V mod, that reduced the PSU noise dramatically, I now hear the wind noise from the window and the fridge noise 2 doors down more than the PC. Cool! There is still some residual noise, afterall there are four fans and 2 hard drives in there...

It was pretty simple and took about 20 minutes. Workspower has very small heatsinks in the PSU, they look like 2 little aluminum plates. I hope I won't fry the PSU. I am monitoring case temps, it seems to have stabilized at around 32C, however I will disable standby and leave the PC on overnight to check PSU temp and case temp. I hope I will find the PC still running :)

The airflow is obviously less than before through the PSU, and the air feels warmer. While opening the PSU I saw that it has a fuse and has a note saying "Over heat protection". I hope that would help protect the PC from being damaged in case overheat occurs. I hope not, this is an HTPC, so CPU load will be around 20-30% max and no heavy AGP card draw either. Will see...

Thanks dukla, and Mike for the guide.

dukla2000
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Post by dukla2000 » Sun Dec 14, 2003 4:28 am

Good news - now for the next noisiest item ... :D
soundOFsilence wrote:Workspower has very small heatsinks in the PSU, they look like 2 little aluminum plates. I hope I won't fry the PSU.
Small heatsinks are a generic problem (seems to me) with these 120mm fan psus: however even the slowest 120mm fans should be pushing 20cfm (in free air) @5V which ought to be more than enough for most psus.

soundOFsilence
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Post by soundOFsilence » Sun Dec 14, 2003 12:21 pm

Case temp rose to max 33, however mobo temp reads around 40, cpu is around 46 or so. A little high, but probably sustainable...

I was looking at the airflow in the back, the 80mm case fan is stealing all the air that comes the front since it has unbostructed air path, the PSU is getting the leftovers, and very little air comes through and out of the PSU.

I was thinking, what if I reverse the rear case fan to pull air in so that there is positive air pressure inside, and the PSU gets all exhuast airflow?

Or how about reversing the PSU fan so that it sucks air through the back and its heatsinks, and all exhaust is through the case fan? I had read somewhere that positive pressure was better than negative.

What do you guys think? Which of the three options would yield the best result?

ghowarth
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Post by ghowarth » Sun Dec 14, 2003 4:11 pm

exhausting hot psu air into your case is not a good idea - your case temps will go up lots. I tried that once before, and my temps didn't stop rising, haha. Run a test if you like, it's pretty easy to do.

soundOFsilence
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Post by soundOFsilence » Mon Dec 15, 2003 12:45 pm

I may consider reversing the rear case fan then, this would create positive pressure inside the case (front AND rear fan blowing into the case), with the only outlet being through the PSU. Anyone tried that?

tay
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positive pressure

Post by tay » Mon Dec 15, 2003 2:30 pm

positive pressure is largely a myth. Ralf Hutter is a big proponent of it being poopoo, and my own experience has shown no difference in temperatures with positive presssure or not. I run a 1 front fan to cool the HD and 3 fans exhausting (incl PSU).

If your case fan is sucking all the air out, slow it down a bit? Increase the speed of your PSU fan to 7V or 9V. That may help.

Do some tests and let us know :)

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