Pentium D 805 came out about 17 years ago. Back then, PSUs were about 60% efficient.
A peak load ?? That seems a little hard to believe.
PSUs tend to be most efficient near peak load*. Efficiency drops the further away from it you get. Just make sure you're looking at the right number. Here's a contemporaneous source, in case there's any doubt about whether they same principle held back then:
www.anandtech.com
In 2007, Anandtech's roundup of 400 - 450 W PSUs found peak efficiency ranging from 75% (outlier) to 85%:
Their roundup of 750 - 900 W PSUs found peak efficiency ranging from 81% to 84%
So, to compute the PSU's output, you really need to ask
@Amdlova what PSU was in use, or at least how many W it was rated for. Also, those articles include different efficiency data for 230 VAC, so that's another relevant parameter.
* This is one reason not to buy a PSU rated massively beyond the load you expect it to experience. Leaving
some headroom is definitely wise.