Power Supplies

I am "fighting" with potential vendors over what size powersupply is required for our new systems.

Here is the current spec:

- Intel Xeon W3570 (3.2 GHz)
- 12Gb DDR3 1333 MHz ram ECC (6 DIMMS)
- nVidia FX1800 Video Card
- 300 GB, 10,000 RPM HD

Xi says I need minimum 750W (850W would be preferred)
Dell says 525W is enough

How big of a power supply is required?

We work on large assemblies and do a lot Simulation as well.

Any thoughts?SolidworksAdministration