If you're experiencing odd lock-ups with your computer, chances are pretty good that they're caused by an overheating problem. There are two common causes of these problems. The first is inadequate ventilation. This is most likely a problem with a home-built machine rather than a pre-built machine, as many people seem to think the best way to deal with heat is to add more fans.
When building your own machine, you need to ensure that there is adequate ventilation both into the case and out of it. Typically, the fan in your power supply draws air in to cool itself, then the air is redirected out the bottom. Since most PCs have the power supply mounted at the top back, that air is going to hit the portion of the motherboard that has the main CPU, or sometimes the main heat sink for the motherboard chipset.
As it passes past each section of the machine, the air is getting warmer and warmer. Where does it go?
Most computer cases have a place to mount an auxiliary cooling fan under the power supply, adjacent to the back panel connectors. but often the fan itself is missing. If you don't have a fan there already, and suspect overheating problems, you definitely want to add one. In most cases it will be positioned so that it blows air OUT of the case.
In most machines this is also right next to the video card, which likely generates as much heat as the main CPU, and perhaps even more. The more beefy your video card, the more heat it's going to generate, so the more important it is to have a good exhaust fan installed.
Many computer cases also have mounting places for fans underneath the front façade. This is typically adjacent to where your internal drive bays are located, so that fans can pull in cool outside air and blow it past your hard drives. If you just have a single hard drive and optical drive, these fans are usually optional. But keep them in mind if you're having to deal with overheating issues.
Poor Heat Transfer
The other common cause of overheating is a bad thermal connection between the CPU and the heatsink mounted on top.
I haven't really been using my desktop computer much these last several months. I've been working mostly on my laptop. But back when I was regularly using my desktop computer, I had noticed that it was having an overheating problem. I downloaded a CPU temperature utility
and it told me I was running at over 80°C when more or less idle. That's more like what you'd expect if the machine was under heavy load and dangerously close to the point at which things stop working reliably.
I'm pretty good at troubleshooting such problems, but like everybody else I get lazy sometimes, so genius tech troubleshooter that I am, I dealt with it by taking the side cover off and aiming a small desk fan at the inside. That seemed to more or less take care of it for the moment, so I never really addressed the problem properly.
It wasn't long after that I ended up working mainly with my laptop, and subsequently I ended up with the desktop machine in storage anyway. Out of sight, out of mind, right?
Until yesterday. I needed to access some files that were on the desktop machine's hard drive, so I took it out of storage and hooked it up. After I copied the needed files over to an external hard drive, I continued to play around with the machine, playing a few games I didn't have on the laptop.
And of course it had the overheating problem again. It even locked up on me a few times while I was playing World of Warcraft. However, I didn't have the little desktop fan handy, so I decided to deal with the problem the right way: find and fix.
This machine had fans in the right places, providing good ventilation. The case temperature wasn't noticeably elevated. So I suspected that the problem was either that the fan and heatsink was not seated properly on the CPU, or else that there wasn't a proper application of thermal grease between the CPU and heatsink.
So I took the fan off to have a look, and sure enough there was only the slightest little thin film of grease in place. Went to Fry's and got a tube of grease. It was on sale but probably still one of the most profitable items in the whole store.
When I got back, I applied the grease to the heatsink, making sure to completely cover the area that would be in contact with the CPU. The main trick to thermal grease is applying the right amount. Too little and it doesn't work. Too much and it doesn't work. Make sure you look at the illustrations in any documentation that is included with the grease and/or fan & heatsink.
After the grease was applied, I put the fan back in place, connected everything, and powered up. Upon reaching the desktop, the first thing I did was run the thermometer program. At first, it was showing me numbers in the mid-50's, which seemed much more reasonable, but I noticed they were steadily rising, and just a moment later it was back in the 80's.
That's when I noticed that the power cable for the fan had gotten tangled up so the fan wasn't turning. I powered-down, fixed that problem, and tried again.
That did the trick, now my idle temperatures are in the high 40's to low 50's, more or less where they should be.