Originally Posted by .?.

Hi everyone, thank you for the helpful information and good replies.

Today I threw in an old 300W power supply as a replacement, but also downgraded my graphics card to something that needs no extra juice (radeon 9200). The system works again. It was, afterall, a power supply problem.

I'm so glad that I didn't have to replace any main parts. Probably I'll buy a new power supply anyway, and also a proper cooling system. At the moment it just has the standard cpu fan on there, which seems to be useless.

Thanks again, and I'm happy you guys helped me get out of this without any major probs.