Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a desktop computer that I intend to use as a Linux server. I assembled all components and the computer properly boots in Ubuntu, and works fine, however, the power supply fan does not turn down after the initial power on. On a previous computer I had, the power supply was starting noisy when turning on, but was turning down after few seconds.

I am not an expert in power supplies, but I have the feeling that either:

  • Something is wrong with this cheapo powere supply (I got it with a case for under $50)
  • Something is wrong with the configuration of the power supply. But I connected everything properly, and nothing in the BIOS setup forces the fans to always be on.

Any idea what could be wrong ? Can it be the power supply that simply does not turn fan off properly ? If this is only changing the power supply, I don't mind getting a better one at the local computer shop.

Addon: Is it possible of a power supply which does not have this setting to turn the fan down after a while ? I also noticed in the older computer that it did not have this four-pin connector that the new one has. It is actually also properly connected on the motherboard.

share|improve this question

migrated from Jan 31 '12 at 19:03

This question came from our site for system and network administrators.

Try resetting the BIOS to defaults, especially the part with POWER MANAGEMENT. – Vick Vega Jan 31 '12 at 18:22
How many pins are on the fan's connector? – vcsjones Jan 31 '12 at 18:28
Are you sure it is the power supply fan? From what I see the gpu/cpu fans are the more likely to change after the system is on, not the power supply. Are you sure you don't simply have a noisy fan? – Zoredache Jan 31 '12 at 18:31
If you're going to be using that as a production server, I'd suggest popping for some quality components. Or better yet, a quality server from a reputable vendor. Unless you don't have much of a network to administer, your time is better spent working on more productive tasks. – Magellan Jan 31 '12 at 18:32
Everything is brand new equipment, received from a retailer. I WILL check the fans to see which one is making the most noise. If this is the power supply, what should I look at ? – jfmessier Jan 31 '12 at 19:00

I bet it's the power supply itself that has the problem. The speed of the fan would be controlled by the temperature of the PSU. The mother board would not know the temperature of the power supply.

share|improve this answer
So, if I determine that indeed the noise comes from the power supply, I should just replace the cheap one with a real, performing one. This one is a no-name of some kind that came with the casing. I don't mind buying a new, better one. – jfmessier Jan 31 '12 at 19:51
After doing some research it looks like there are other people that have had your same problem and they have verified that the power supply works right on one computer but not another. I guess the voltage draw by the mother board also affects the fan speed. I still think a better power supply would always work right. – sjbotha Jan 31 '12 at 20:42
Fan speed control is not an obligatory feature of PSU. – stim Jan 31 '12 at 20:57

It's just a peculiarity of low-cost cases. Since your PSU is very cheap - it is quite possible that manufacturer didn't implemented fan speed control.

Best practice is always buy separate PSU if you want to save money on case. Such devices are not only noisy, they are unreliable and can be dangerous especially under heavy load. Economy does not worth a risk especially for a 24 / 7 mode.

share|improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .