I could use a pair of Seasonic X1000's that I have, but I also have 4x of the DPS-1200's from an old HP DL580 just sitting around.
I also have a pair of DPS-700GB PSU's from a HP DL360. These would be under-rated since the L3+ Draw is rated at 800W.
I was told by others to get a PSU rated at least 20% higher than the load.
I would say ideally 50-80% for efficiency on these server supplies (full bridge topology). You should invest in a DPS1600 or greater.
Confused... Sidehack just recommended <= 1KW max due to fire issues when PSU doesn't shutdown on overdraw...
Also, 66% of 1200W is 792, right at the 800W mark for the L3+...