CPU fan running fast

I cleaned out the dust/dirt from my entire PC yesterday. I cleaned the CPU and heatsink mating surfaces of all the old thermal compound and applied a fresh (and I believe appropriate) coat of Arctic Silver to the mating surfaces and finished re-assembly and connection to the internet.

Now when I run a youtube video or the disc defragmenter, the CPU fan runs faster than it did prior to dis-assembly and cleaning. I'm afraid of burning the CPU up. Any ideas of why the fan is running faster during the above mentioned programs (and others) than it was before?

Note: The fan didn't SEEM all that dirty to begin with, so I'm not fully convinced it's just spinning more freely and, again, I believe the appropriate amount of thermal compound has been applied so I'm also not so sure that there just isn't enough compound on the mating surfaces of the CPU and the heatsink (Although I suppose it's possible). Any thoughts? Thanks.

 

with cooling fans, sometimes you can blame the wrong one for excessive noise. The video card fans are usually the loudest.

But use "speedfan" it's free utility that can give you realtime cpu temps while under windows.

This webpage has the max tempeature of most cpu's.
http://www.hardwaresecrets.com/article/143

 

Checked CPU temp w/Everest software. Highest reading was 63 degrees C (very briefly) with 3 windows open (1 of these was a youtube video, 1 was my Yahoo account and the 3rd was the Everest window). Do either of you know what "normal" CPU temp should be and under what conditions? The computer itself is performing as well as it ever has.

The fan that is running more often now is definitely the CPU/heatsink fan. I just don't understand why it is running more frequently than it was prior to the clean-up and thermal compound application.

Thank you both for your input thus far.

 

58-59 degrees Celsius.

 

O.K. I'll give it a try.

 

Well, it seems that I re-installed the cooling fan backwards (although I could have sworn I didn't). Now running @45-49 degrees Celsius under a load. So, human error was the problem. Thanks for your input once again.