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I recently installed a second graphics card (ATI 5770 in crossfire), and cleaned out a lot of dust from the PC. For some reason however the 'fan noise' is much louder, and I can only think of a few reasons:

  • The two graphics cards have paired up to be noisy.
  • The powersuply is working overtime to feed my power hungry cards.
  • The whole box is hotter, making the CPU work harder to stay cool.

Which of these is most likely, and how can I make it quiter? FWIW my powersupply is a corsair 650W (maybe 750W, but I don't think so) and my CPU is a Phenom II X4 955.

Update:

I've just installed SpeedFan on my windows boot for t his machine, and the temps are up around 60-80c That 80c is on my second GPU. I'm guessing that's not good What can I do in light of this?

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Do you have enough spacing between the two card? Can you identify the source of extra noise? i.e. which fan cause more noise? From my rough calculation, your PC shouldn't consume more than 450W so 650W PSU will be sufficient. –  chmod Jan 16 '12 at 17:18
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Do you have an application to monitor interior temps? Speedfan is a common one. This may give you additional info on what is going on. almico.com/speedfan.php –  Dave M Jan 16 '12 at 17:22
    
@DaveM I can't find an alternative to that on linux. Any suggestions? –  Pureferret Jan 16 '12 at 17:39
    
@chmod It sounds like it's from my CPU –  Pureferret Jan 16 '12 at 17:41
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btw you maybe should adjust the title, although its funny it misleads people having the same problem. –  Baarn Jan 17 '12 at 1:22
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3 Answers 3

up vote 5 down vote accepted

A few ideas:

  1. did you remove the heatsink from the CPU without without replacing the thermal paste?
  2. When cleaning, you might have missed a chunk of dust on a fan and thrown it off balance.

Boot it with the top off and give it a careful listen. If it's not obvious where the noise is from, shut down, remove the new card, boot and see if the noise is there.

If the noise isn't the new card, if you gently touch a running fan, it will slow it down for a half second or so (don't stop it!). If the loud noise doesn't change, it will eliminate that particular fan as a possible source of noise. If the loud noise changes, you found your culprit and know what needs more careful cleaning or replacing.

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I touched the cpu fan gently for 1/4 of a second and the noise difference was noticeable. It's (accordign to xsensors) spinning at about 3200 RPM and the cpu has a temp of ~40C (104F). Are these normal/good figures? I'll inspect the dust situation once I have time to get at it properly. –  Pureferret Jan 17 '12 at 9:23
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It sounds okay to me for speed and temperature. The engineering specs would have the details. I clean this kind of thing by shutting the machine down, unplugging it and using a small stiff paintbrush to brush the dust off each blade of the fan. It may not be possible to get under the fan. Try the top only first, plug it in and see if the sound is there. If it is... try again or try canned-air. If it's still a problem, you're looking at removing the fan/heatsink and cleaning it thoroughly or replacing it. (BTW, if you can live with the noise, the machine is probably ok.) –  mgjk Jan 17 '12 at 16:00
    
I'll give it a clean, but I think I can live with the noise! –  Pureferret Jan 17 '12 at 16:15
    
I've just installed SpeedFan on my windows boot for t his machine, and the temps are up around 60-80c That 80c is on my second GPU. I'm guessing that's not good. –  Pureferret Jan 19 '12 at 19:29
    
It seems normal for being under some load: hardocp.com/article/2009/10/12/… I'm not a gamer though, they'd know better. –  mgjk Jan 19 '12 at 19:56
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Sorry if this is too obvious, but assuming the new card has a fan, are you sure it's not simply the additional fan?

Another idea... sometimes stray wires inside for power connectors or drives might move in such a way that they slightly rub against a fan causing noise. It may be that it will only happen with the cover on, so carefully removing the cover with the system running might be necessary.

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It may also be that the bearings in the fans are wearing out, and it's more noticable now that there isn't dust clogging them up/slowing them down. –  Shinrai Jan 16 '12 at 18:35
    
@Shinrai the CPU is 2.5 yrs old, would they wear out that quickly? –  Pureferret Jan 17 '12 at 9:24
    
@Pureferret - Age isn't a factor so much as dust level, but yes, I wouldn't be surprised at all. –  Shinrai Jan 17 '12 at 17:04
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Obviously, a system with that much hardware and power consumption simply is noisy. There is to much fan action going on to keep it cooled. The only real way to get this quiet is a powerful liquid cooling system, attached to the CPU and both graphics cards. Of course, this is an expensive solution requiring some technical skills (or someone who has them). If you are working on a budget, there are some minor things to do:

  • make sure that you use quiet fans at all (have a look at the internet to find out how much noise your fans make and look for more quiet alternatives)

  • use a well build housing that ensures a good airflow (thermaltake, etc.)

  • use big heat sinks

  • use vibration dampers below all fans

  • dust filters are fine, but they should not be directly next to your fans

  • if possible, leave some space between the graphics cards

  • use big fans with low speeds

  • use as few fans as possible

  • last but not least, clean up the PC regularly (2 times a year is a good cycle) using compressed air for best results

All of these will bring very little enhancements, but many little enhancements make a big one.

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