please reread SDH's previous post to you, in it he plainly states that HP has "NEVER" cleared the 5590 for use in the z600
and that it most likely will not work, but you have nothing to loose by testing the cpu once you have the 130 watt performance heatsink. and that he would like you to post the result along with the information on your motherboard revision
i personally recomend just trying one 5590 cpu to start, and if it boots, then try the second cpu
as to if the 650 watt supply, it depends on if you have two 130 watt cpu's and how many memory modules installed the number of drives installed and what type of video card (wattage draw) installed