I'm running a Dell Dimension 8200 2.26 ghz P4 with 768mb RDRAM.

I tried upgrading it to a 2.8ghz / 533 SL7E2 P4 to no avail. The fans work and I can hear the HDD spinning up, but the BIOS won't load.

I've tried resetting the CMOS & Flashing the BIOS. I don't have enough repeaters so I can't try booting with one stick of RAM. 

It still boots just fine with the old CPU after my attempted upgrade, I have no idea why it's not working; please help.