--***ONE THING BACK UP YOUR IMPORTANT STUFF NOW***---
(Though my guess is you already have, as you don't seem to be a noob)
I'm getting that it wasn't always like this ...
Analysis point by point:
Things that move & therefore make noise (as Rich mentioned):
2) Rom drives
3) Hard drives
1) You can find out if it's the fan (or which one if there are more than one) by using a soft bristle brush to stop the fan for a second if you can reach it.
2) Make sure there is no disk in the DVD, should eliminate that as an item.
3) Likely if it were the hard drive you would have much more trouble than just noise, noisy hard drives are usually accompanied by major crash/lock-up issues, but still, if you can remove it & power the unit up that should eliminate that as a possible source (though without windows running you may not get enough heat to kick the fan up)
If you are not up to the disassembly/assembly then it’s tech work from there.
Short term Muhammad’s trick is likely to give you more time to work on it & maybe lower overall heat damage that may be occurring.
Long term, I'd call HP, and see if they will warranty-fix it or supply parts, as these models are known for heat issues they are usually happy to help, for a fee, but the fee is often lower than I would normally expect from the manufacturer on parts for these units. (I suspect they are trying to dodge a class action in the long run)
Valid points but Low grade to: Muhammad, certain models of HPs (dvXXXXs among them) do have a reputation for cooling issues. But I hate Bubble-gum & black tape "FIX"s. The “low grade” is for presenting his option as a solution, rather than the temporary work-around that it is. Continued to use an overheating unit WILL eventually result in a dead motherboard or other parts (sometimes the video is the source of the heat issue.
He is correct that high CPU temps can cause the thermal management system to kick the fan up to MAX RPM. (A bad sensor could also cause this, BUT these models are known for running hot)
B) Rich, Mich, & Chicken1 are on track.
C) D R needs to think in reverse, BLOW into the out/exhaust, accumulated dust on the other side of the radiator needs to move backward as it isn't going through, and clogging things up, there are often strands of pet hair, and other fibers trapped in the cooling fins, holding dust trapped on the fan side of the radiator.
Interesting List of answers, jokes, trash, & TROLLs! (Your pretty face gets lots of attention LOL)
My "little Grey Cells"
(been nose-into-computers since Comadore64s were actually used to teach BASIC. Un-Hun, that was, early 198x so I'd rather not add up the years.)