Computer Hope

Hardware => Hardware => Topic started by: jtr on November 17, 2009, 09:04:17 PM

Title: CPU fan high speed on boot, gradually slows down
Post by: jtr on November 17, 2009, 09:04:17 PM

I run Vista on a homemade desktop.  My CPU fan had never changed its operation in the 6 months I ran Vista until a few weeks ago.  Previously my CPU fan would always come on at its highest velocity immediately after starting.  After about 20 or 30 seconds it would gradually slow down, and within probably 10 seconds it would be at the appropriate level.  (I have a continuously variable speed CPU fan, and I have it set pretty much in the middle.)  About a month ago, it started staying at maximum velocity well after the system is booted, and 1-2 minutes after Vista is fully loaded it would then gradually come down.  Other times it would start out the predetermined speed and would not be at high velocity at all during the boot sequence.  And yet other times it would perform its old standard and drop velocity about 30 seconds into boot.  I formatted and reinstalled Vista about a week ago because I was having some issues in addition to this and tried to format as a cure-all, but this issue remained.  My assumption is that the problem may lie with the BIOS, but I have not actually rummaged around in there yet.  Any ideas? 

Title: Re: CPU fan high speed on boot, gradually slows down
Post by: patio on November 18, 2009, 07:37:46 AM

There are probably accumulated dust bunnies in there causing it to take longer to cool to the proper operating temp...

Time for some housekeeping.
Remove all power to the machine.
Remove a side panel and use a can of compressed air to clean all fan's and housings and any heatsinks you see including the vid card.
Use a QTip to hold the fan blades in place when blasting them to prevent damage.

As always when working inside the case take anti-static precautions...

Title: Re: CPU fan high speed on boot, gradually slows down
Post by: jtr on November 18, 2009, 11:29:43 AM

That's not it.  It's clean.

Title: Re: CPU fan high speed on boot, gradually slows down
Post by: Computer_Commando on November 18, 2009, 11:49:36 AM

CPU fan speed is determined by CPU duty usage and how hot it's getting.  If it's not oveheating, don't worry about it.  It's probably getting to 100% usuage due to some program or update change, or malware or spyware.

Title: Re: CPU fan high speed on boot, gradually slows down
Post by: patio on November 18, 2009, 02:16:34 PM

Quote from: jtr on November 18, 2009, 11:29:43 AM

That's not it.  It's clean.

OK i give up...

Title: Re: CPU fan high speed on boot, gradually slows down
Post by: jtr on November 18, 2009, 04:01:51 PM

Even though this is happening during the boot sequence?  I'm not overly worried about it.  It's just weird, and a bit annoying.