Freezing Problems on Gateway

I have a Gateway GT5674 desktop that I'm fixing for a friend. It started freezing on him about 5-10 minutes after bootup. There was no BSOD or anything and I thought it was weird so I decided to unhook the HDD and and boot to linux on a CD to check if it wasn't just the OS, and sure enough Puppy linux froze about 5 mins after bootup. So my question is it more likely to be the motherboard, CPU, or RAM that is bad? It's hard to tell because there was never any BSOD. Any help would be appreciated. Thanks.

Well, if the cpu got overheated , it would shut down, so, i am leaning towards the RAM .

First I would download cpu-z and gpu-z to monitor the temps (free).

Then I would check event viewer

There are several ways to find what the problem is. The best is to go into event viewer (type eventvwr in search). Event viewer (local) and look for errors listed in the last day, week, etc. Then go to the windows log>application tab. Finally the windows Logs>system tabs.

You want to look for all errors (they have red in the left column ).

When you find them you want to look for critical errors that say app hang, app crash, or anything that relates to the problem.

When you find them please note the event ID, and the source codes and tell us what they are.