Got 2 PSUs from a Compaq 9000 server, including the backplane + cables.
Have not tried to connect anything yet.

Anybody have an ide how to jump-start it ? Just use the ATX like cable ?
And then with all the cables, I can easily measure where I get 12V out.

It is rated 750W output @ 220V. 2 of those on the backplane = 1500W out.
Should be more than enough for 3 units, probably fine for 4 units.

4x360 @ wall = 1440 * 0.85 efficiency = 1225 power draw.

Did anybody measure actual power consumption by one Antminer S1 ?

The PSUs are rated 6A @220V input = 1320W, so 750W out is pretty poor. But maybe they are efficent, and the 1320W is startup peak.