OK so here's the deal. I upgraded my PC's mobo, CPU, videocard and RAM (so, everything but the HDD, case, PSU and DVD Drive, then). Everything works fine... Except some times the PC won't boot up. Sometimes I turn it on, I see the mobo splash screen, then everything turns off again, and then it resets. Other times I get to the Windows loading screen, at which point the screen goes off and so does the PC. This usually happens when I start up with a CD in the disc drive, but the weird thing is, it happens when I take the disc out and reboot as well. But then when I go awhile just booting regularly, without any discs in the drive, it works just fine.
I'm thinking it's a PSU issue, as my PSU is nearly 2 years old and 450watt. It's an Antec PSU, that came in the case (Sonata II). My new system is Abit IP35-E mobo, ASUS Geforce 8800GT, 2GB DDR2 RAM, and Intel Q6600 quad core.
I'll probably replace the PSU anyway as it is 2 years old, and I want to be on the safe side, but I'd like to know if anyone has any ideas as to what's causing this.