I just tried 8 on my GX270 on a whim, and, oh my no.
Same error code, 0x0(some more zeros, I lost count... don't quite know how many make up a hex address, is it 8?)5D, though shouldn't the Socket 478 P4s all support NX? Is it just Dell being stupid with their BIOS?
I know for a fact-ish that...