Hi there, i had encountered pc sudden freeze and auto-restart randomly problems. Would like to have some opinion from you guys.

My pc rig is an old p4 system, 2.4ghz, mobo p4vmm2 elitegroup, ram 512+256mb apacer, AGP card ATI Radeon 9250 128mb 64bit.

Firstly, i had tested my ram. By plugging out the ram, let the system ran in 512mb for the first time, and 256mb for another time. However, the pc freeze and auto-restart problems still occured.

Secondly, i tested the graphic card, by plugging it out and let my system ran with integrated graphic on MOBO. Seem like the freeze and auto-restart still occured.

I had even defrag the HDD. Tested it with S.M.A.R.T. Seem like ok.

So, i suppect it is caused by the overheating of my CPU. So, i clean all the dust of the HSF and replace with some new thermal paste.
After that, I monitor the temperature change of my processor by EVEREST home edition. No-load average temperature is about 44-46oC, and full load temp is about 55-56oC. When the processor is at no-load, the freeze and auto-restart seem like not so obvious but still occuring randomly. However, when at full-load, the freeze and auto-restart happened significantly(freeze may occur from 1-10 minutes).

Finally, i switch on my air-cond in my room and let my pc run at full-load and monitor the temperature changes. The temperature went down a bit and maintain at about 53-54oC. But i can see that my pc running very smooth, with full-load running about 30 mins. After that, I switch off the air-cond and do some internet surfing while monitoring the temperature changes of my processor(47-48oC). About 20 minutes, the pc started to freeze again.....

So, you guys think that the freezing is caused by the overheating of processor or PSU???