I have a XPS 730x with a 0P270J mother board. I am looking at ADDING two  eVGA GeForce GTX 570 HD SuperClocked Graphics Cards (012-P3-1573-AR) and two VisionTek 450W Dedicated Graphics Power Supplys.
 I have looked a NVIDIA's compatibility charts and the do not list this mother board?
 The cards need also (i think) 550watts. I cannot find any info on how MUCH wattage the motherboard supplys to each card so not sure if adding the 450 watts is anough?
 I hope I explained this correctly. I will supply any info you might need.

 Based on the info provided i would get at least a 650W PSU...
P.S. Don't buy a cheapo unit...

As far as the addon VisionTex UNITS i wouldn't trust them if i spent that much on a vid card...just my OPINION. The pc's psu is 1000w. I think the Mother board supplys 75w? not sure?
 I cannot find a larger Dedicated Graphics Power Supply that fits a 5.25” Bay?
 ThanksBTW The "VisionTex"? Yes there are other brands (all are no larger than 450W)(that I can find). I have not checked into the quality yet. Want to make sure they will work first.
 Thanks again!!