If it's a faulty motherboard, I'll not be happy at all. I've already replaced the motherboard with a nice, reliable ASUS, and I was hoping that would solve it.

I agree, both GTA games are quite badly ported, but the first one runs just fine on my machine on the same minimal settings. Argh. But I think you're right. There's no reason, if the hardware has no difficulty rendering the graphics, that it should overheat so quickly.

If I wanted to get into watercooling, what would you kind people suggest?