CPU running hot, fan running continuously, it's not the dirt!

[One Sock]

I have an HP laptop dv9000, running Win XP. I run Speedfan to monitor temps. All of a sudden, I noticed the CPU was running at least 10 degrees C hotter than usual; i.e., with CPU at 0% it was running at least 40 degrees where before it was about 30.

I took the computer apart and cleaned the dirt out of the heat sink.

Now, as soon as I turn the computer on, the fan comes on and runs loudly and continuously, regardless of temp. And the CPU is STILL running about 5 degrees warmer than usual!

What is going on?!?

[Geek-9pm]

Please provide more information. For many CPUs 40 C is  mild.
You may have a background task running. 
What does the task manager say?

[One Sock]

The CPU is an Intel T7200 2 GHz Core 2. Yes, I know that 40 is not that hot (at 100% load it runs above 60) but the point is that the idle temp has jumped about 10 degrees for no apparent reason. This suggests there is some malfunction. I've had the computer about 5 years, and it's always idled at about 30, maybe 35 in high ambient room temp.  Task Manager and Speedfan both show CPU usage at or very close to zero when I'm not doing something.

And there's also the fan: it comes on IMMEDIATELY when I turn on the computer, even if the computer has been off overnight. The fan runs at a constant high RPM, and it's loud and annoying! It does it in Windows, in BIOS, and in BartPE. My computer has NEVER done this before!

Would a fault in the fan itself cause something like this?

[Geek-9pm]

You room temperature is about 25 C.
What eat temp do you see after the machine has been off for an hour and your turn it on? It should start near 30 and more up to 40.

Normally that Intel design can go from 0 to 100 C and be inside its rated range. It is a mobile processor, which means it can throttle up and down as need be. That why I thought you had a new background process running. But it it does it in the PE, it would not be a background task.

It is not a malfunction. it is an aberration. In other words, a unusual departure from expected or historical behavior. It is not a failure.

In bother forums people have asked about the aberrant temp readings of the Intel T7200 and thee is no clear answer.

[Kurtiskain]

Did you remove and replace any old thermal paste or thermal tape?
This can make a 3-8 Degrees difference when replacing it with a high quality solution.

[One Sock]

I've been using Arctic Silver 5 ever since I replaced the motherboard about 2.5 years ago. I cleaned the old paste off and put on some new when I cleaned the heat sink last week.