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Noisy PSU fan, add a resistor?

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October 10, 2013 12:29:43 PM

XFX 750 pro PSU is quite noisy. It sounds like the fan is running at about 80% all the time, idle, load or startup doesn't matter. The Noise is almost all air moving and the exhaust air is cold so it seems that the PSU fan is running faster than it should...

I've already had a sneaky look inside so my warrant is already void. and I'll stick a resistor to the fan if needed..
The temp sensor is safely attached to the largest heat sink. I have recently turned the PSU upsidedown now and that's stopped some of the noise which was a kind of "whirring" in the gap between the fan and the floor of the case, but the PSU is still the loudest thing in my rig..
Is it worth throwing a resistor into the fan line? Anybody done it?
October 10, 2013 12:36:20 PM

In general, the fan is designed to keep the power supply cool enough to run properly.

If you do go about adding a resistor, you will have to pick a value based on the fans current draw. If the power supply is lowering the voltage, it may mess with the resistor value as well.
http://www.blackfiveservices.co.uk/fanspeed.shtml

I have a Antec EA 650 that is very loud as well(loud for a power supply that is running VERY cool as well). I have thought about replacing it with a more quiet fan.

If you can not handle it, you can go for it, but keep an eye on the unit to ensure it is still running cool enough.
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October 10, 2013 1:20:33 PM

Thanks, that's a handy link, brings me back to physics class! The PSU fan is rated at 0.44A seems it would need a 20 ohm resistor. Its a 135mm fan as usual..
I have a 140mm fan lying around that's rated at 0.18A that I might throw in too and see if its a bit quietier, it will just about squeeze into the PSU, just means drilling a few holes in something.
Also it doesn't seem like the PSU ever lowers the voltage because the fan is constant weather stock idle or overclocked, so I should be ok with the 20ohm..
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October 10, 2013 6:22:17 PM

You can meter the fan if it is not PWM. That would let you know if it is or is not changing the speed.

If you wanted to go lets say 7/8/9/ect volts with ANY fan, you would use a voltage regulator to shed those extra volts. Fan load would not longer be a part of the equation :) 
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October 11, 2013 11:35:55 AM

Right so this is what I've done at the moment,


Uploaded with ImageShack.us
I removed the ADDA fan and the cover, and just sat my 140mm Storm Stryker fan on top. I've connected the 3 pin connection to the 4 pin system fan header on my mobo which seems to be running it at either 5V or 7V not sure which, but its running around 650-700 RPM and totally silent. The ADDA fan was doing my head in at 12V!

Going to keep an eye on it for a while to see what if the temp is ok before I run Prime or anything like that. Plan B is to connect to the fan controller on the case if needs be. before I throw the cover back on.

I'd like to have it connected to a temp sensor for that extra security and I know messing with PSU's can be dodgy, but to hell with it!!!

Any thoughts, tips or abuse is welcome.. :-)
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October 11, 2013 12:57:06 PM

All in all that HAS to provide better cooling than the stock fan(its larger and cools an even wider area.).

The lack of the outside casing should also let air flow more freely.

If this works out good, Maybe my EA 650 may get a similar treatment :)  (its not like it uses even half its capacity)Failing that it will get a NF P12 or similar.
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October 12, 2013 12:20:30 PM

Ok so PSU was running fine and cool all day until I booted up Skyrim. PC rebooted itself after 1/2 an hour of gameplay. The air from the PSU was warm, and gameplay was a little jerky before the crash so its a possibility that the 700RPMs just isn't cutting it under prolonged load.
It could also be my 4.5Ghz overclock.
I think I might hook up the PSU fan to the fan controller on my case, and just ramp it up when playing games. Tried getting it hooked into Speedfan to work off the GPU and/or CPU when the temps go up but can't get it going.
Anyone ever actually get Speedfan to actually work?
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October 12, 2013 3:21:10 PM

I had made some old posts about speedfan, but some of the images may be gone. No offsets are needed anymore

http://www.tomshardware.com/forum/247094-30-help-speedf...

Some boards need you to change the fan control mode in the advanced settings to allow speedfan to control them as well(this takes over for motherboard control).


Also note that some boards have more than one fan header connected together making multiple fans control together.

If you are still stuck, I will try to help further.
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October 14, 2013 3:51:19 PM

Finally sorted, more or less. Took a while to get speedfan running at startup with Windows 8. It wouldn't start up with shortcut in startup folder, creating reg entries, ccleaner or task manager. I had to set it up to run as a "scheduled task".

Anyway, I have the above fan connected to the SYS_Fan connection on the mobo, running at 55% which is about 700RPM, and its set to gradually ramp up when northbridge goes above 40c OR my GPU goes above 40c, using the "fan control" tab in Speedfan.

I figure that either prolonged high CPU usage or GPU will pull more power so I'm covered either way; although only the GPU seems to heat up the power supply.
I think this partly warm air from the GPU itself though, because prime95 doesn't seem affect it. But then again there's about a 200W difference between Idle and load on a 670.
Either way, boost the fan for games and heavy work, keep it quiet for web browsing etc... Job Done!
P.S.
OpenHardwareMonitor is really handy too, allows you to adjust fan speeds and it has the option to add on screen gadgets. A lot handier than the old hardware monitor..
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October 14, 2013 4:34:44 PM

nukemaster said:
In general, the fan is designed to keep the power supply cool enough to run properly.

If you do go about adding a resistor, you will have to pick a value based on the fans current draw. If the power supply is lowering the voltage, it may mess with the resistor value as well.
http://www.blackfiveservices.co.uk/fanspeed.shtml

I have a Antec EA 650 that is very loud as well(loud for a power supply that is running VERY cool as well). I have thought about replacing it with a more quiet fan.

If you can not handle it, you can go for it, but keep an eye on the unit to ensure it is still running cool enough.


True. I had a very very quite OCZ ModXStream 600W PSU that even at full load it was dead silent, soon it ended up committing suicide the next hour. http://www.tomshardware.com/answers/id-1833429/thermalt...
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October 14, 2013 8:52:02 PM

I had an OCZ gameXtreme fan start to die. swapped it for an antec pro bb 120mm fan(those things can run forever.). Problem solved :) 

It was not super quiet, but still better than my damn EA650.
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