DFI Lanparty won't BOOT! (DIES)

[HostVisions]

Hi all,

I'm trying to assemble a DFI Lanparty P4 system with prescott 3.2 P4. Got the MB in the case, light her up, she posts up (CPU speed shows, memory shows) gets to 'detecting IDE drives' and shuts down. Never seen this before. I unhook all drives (SATA and EIDE) with the same result. I can't 'DEL' into bios either.

Any ideas? I've got an ATI X800P in her, wondering if that's the problem... (visiontek X800P)

Thanks