Noisy Processor fan

[Cool Buddy]

For the last few days, my processor fan has become very noisy. I have:

Phenom II X4 840 processor running at stock speed (3.2 Ghz) with stock cooler
Gigabyte GA-78LMT-S2P motherboard
4GB DDR3 RAM (single module)
MSI Radeon HD 5670
2 HDDs (500GB WD Green and 1TB Seagate)
Corsair CX400 PSU

In speccy the processor fan speed is showing over 5000 RPM all the time even when the processor temp goes below 30 deg celcius. I cleaned the insides of the cabinet just a few days back when I noticed this problem. at first it seemed to help, but then it became noise again.

Any suggestions?

 

[xs.dhaval]

Here are my guesses:
1 Something blocking the fan wings
2 Fan may have been slightly disoriented
3 It may be running the other way. (Instead of sucking, it may be blowing on cpu.)

 

[Cool Buddy]

Here are my guesses:
1 Something blocking the fan wings

I cleaned it just a few days back. So unlikely. However, I'll clean it again with a blower this time.

2 Fan may have been slightly disoriented

I think so too. I'll open it and seat it again.

3 It may be running the other way. (Instead of sucking, it may be blowing on cpu.)

Unlikely. I fixed it back in November. It wasn't so noisy till a few days back.

 

[xs.dhaval]

Did you play with your fan speed settings control recently??

 

[Cool Buddy]

No, nothing of that sort.
Actually, I think I just started noticing it and it has always been this noisy only. The noise has definitely gone down after I cleaned it last week.

If only someone could tell me the normal RPM of a processor fan when the processor is running around 30-30 deg Celsius