I don't think it'll be that high on here, probably 400 to 500 watts tops. The CPUs are about 90w each, so that's 360w from them alone. Other than that, there are four 15,000 RPM 36.2 GB SCSI hard drives, 6 GB RAM and nine 120mm 7,500 RPM fans. Video is onboard, sound isn't an option at all, LAN is both onboard and another two ports via a PCI-X card. These things are built to run full load 24/7/365, I don't think they'd give "only" 800w PSUs if they required 700w

As for electricity, I don't pay a cent

But back to the OS issue, HP says these support up to 32 GB RAM with a 32-bit OS?