How do I solve a heating CPU?

Clarifications

You could try giving better air flow to your PC. Also try clearing and dust from the CPU Fan with a dry cloth. Perhaps look into another/better cooling solution.

That is blocking the airways inside your computer. Canned Air is the easiest and safest way to proceed here and just blow it out.

If you have a NoteBook after it's cleaned you need to use a Cool Pad under it to prevent any crud getting sucked into it and clocking the airways again. Something like the Cool Pad from Antec will do nicely but many others of the same type are available

http://www.antec.com/Believe_it/product.php?id=NzImMjI=

If the CPU still overheats you may need to remove the Heat Sink and apply more Thermal Transfer Paste but unless Something drastic has happened or the unit has been pulled apart previously this should only be the last resort and shouldn't be necessary.

Col

Hi if you add more thermal paste, remember more is not always better, the thermal paste should be applies then take a razor blade to spread it evenly and as thinly as possible. (do not put the paste on and squish it down with the heat sink.)
also blowing air is good, but i prefer vacuuming it out , when you blow it out the dust goes everywhere, if you vaccuum it it stays contained.

Dont be afraid to take that calse, heatsink, front covver and powersupply apart. you would be amazed at how much dust can build up.

Also what is the temp in the room the computer is in? if the room is hot, the computer will run hotter.

I did this to an over heating laptop and desk top and immediately they started to run cooler

After you clean it, consider the location. The inside of the box can run up to 90 degrees hotter than the room temperature. so in addition to the comment about the room where the PC is sitting, is it sitting on the floor and possibly the back is closed in preventing it from getting good air flow, or sitting on carpet which can cause it to collect dust quicker, or in front of a window? The other day I replaced a PC (business) that was sitting on the floor undera desk right beside an electric heater, a serious no-no.

I would not take the power supply apart as it holds a charge for quite a while after being disconnected, also be careful using a vacuum cleaner as it can generate static

Everything mentioned above is correct. Many overheating problems are nothing more than dirt. Clean it out, problem resolved.

If not, check into oversize heat sinks for the processor. If the processor heat sink you have does not have a fan on it, get one that does. Buy a high-quality heat sink made of copper, not zinc or an amalgam ("pot metal"). And follow the instructions exactly when mounting it to the processor, such as thermal grease and fasteners.

And you didn't mention it, but are you overclocking the CPU to improve performance? As many tech notes will tell you, overclocking generates significant heat, and will damage the CPU. It may take some time, but the chip will "fry" eventually. You can try to keep it cool, but overclocking causes damage. That is why there are so many warnings against doing it.

Don't use a vacuum cleaner unless it's rated as ESD safe for electronic apparatus.
Dust flowing through a plastic nozzle can generate a lot of static electricity.

Have you tried a tool like "Core Temp" to check exactly how hot your CPU cores are getting whilst in use?