My computer often suddenly only has 10% of CPU capacity

Question

Something like every second hour I run my computer, my CPU suddenly only has something like 10% of capacity. This is not because of some process taking the rest of the capacity, it is the CPU itself that is suddenly running slower. After this has happened I can for example try scrolling a webpage in Firefox, just to see that the process is taking up almost 100% of CPU (seen in Task Manager), and the scrolling repaints something like every half-a-second.

The only way I have found to fix this, is to restart the computer and it will once again run on full speed.

It seems like this happens more often if I have been running programs, which require lots of CPU processing, so it might be related to heat.

Is there any way to diagnose the problem.

EDIT A diagnosis dump from CPU-Z after the slow state has occured can be found here.

Answer 1

Sounds like a heat problem to me. Modern CPUs will automatically throttle back and reduce clock speed if they think they are getting too hot. Download and run CoreTemp, and let us know the temperature(s) including TjMax (or take a screenshot and upload it to imgur).

If high temps are the problem, with a desktop you can take the side covers off and clean out/vacuum up dust, especially around the CPU heatsink and fan (possibly also unscrew the CPU fan to clean dust underneath it). With a laptop blowing compressed air through the vents can help remove dust.

Answer 2

Use a CPU stress testing software outside of windows if you wish to determine whether or not that is the problem. A reboot CD like the ultimate boot cd has this functionality. You may also want to try disabling your startup items to make sure that you don't have a run away process. Run msconfig from the run command in XP or from the search box in vista or 7. Go to the startup tab and choose disable all. Reboot and see if the issue persists.

Answer 3

It sounds like your system is getting too hot and your motherboard is throttling the CPU to cool it down.

Use a program like SpeedFan to view and monitor your system temps.

Additionally, you can check your motherboard’s BIOS settings to see what throttling options are available; usually you can set the throttle level (eg 12.5%, 50%, etc.) or even turn it off.

Answer 4

Based on the dump I was able to determine that you have an HP PAVILION HDX9095EO. With an Intel Mobile Core 2 Duo T7300 processor. Laptops tend to become hotter than desktops due to their large part density, so overheating issues are fairly common.

This sounds like it is a heat issue. As Spectre said:

Modern CPUs will automatically throttle back and reduce clock speed if they think they are getting too hot.

If you use a program like HWmonitor you can measure computer temperatures and fan speeds. The normal temperature average under some load seems to be around 76-88 °C for your processor (as stated by other users). If it is much higher than this, you have a problem.

If you follow Linker3000's thoughts, booting an Ubuntu LiveCD would rule out any inconsistencies. You can use temperature monitors there to see how hot your processor is running. This is a good step to evaluate your system since Linux operating systems are mostly more efficient than Windows.

Regardless to the previous information, I would recommend giving your computer a full clean-out. This general guide will help you in the cleaning process. Reapplying the thermal paste on the CPU will improve the efficiency, i.e. less heat generated, of your computer, it's not necessary, but it's a good idea. This manual will provide information on how to disassemble and reassemble your laptop.