There is no way to "kill" the active PSU ... it maintains minimal power so that the system can be monitored and accessed even when turned "off".  Newer servers are much more efficient with this power level but still do the same thing.
hi, I'm now a proud owner of a Power Edge 840, but I can't figure out how to turn it off without completely unplugging it. Even if I deactivate IPMI, the PSU is still running and draining ~10W. Any ideas?
Turn off Power Edge 840