Windows 7: Dedicated PhysX card: PSU question

So I'm running a GTS 250 as my main gfx card, but I have a 9800 GTX+ just lying around that I was considering using as a dedicated PhysX card. The only question is, will my 700w PSU be enough to power both cards, or do I need to jump up to 750 or 800?

If it's this PSU:

Newegg.com - Rosewill Green Series RG700-S12 700W Continuous @40°C,80 PLUS Certified,Single 12V Rail,ATX12V v2.3 / EPS12V v2.91,SLI Ready,CrossFire Ready,Active PFC"Compatible with Core i7, i5" Power Supply

(rated at 54A on its single +12V rail) I'd say yes.

It has a 6 pin PCI-E connector, and one 6+2 one. I beleve that the GTS 250 and the 9800 GTX+ each want a 6 pin, so you should be OK. (I think I've seen one GTS 250 at Newegg that wants two 6 pin aux. power connectors, which would make things a little more awkward.)

Yeah, that's the PSU. The GTS 250 I have takes 2 6 pins, so I'm looking at having to buy a molex to 6 pin adapter anyway.

I'm a bit surprised that you don't already have one. I've bought a few PCI-E cards in the past few years, and every one that required aux. power came with at least one such adapter. (Retail boxes.)

One bit of advice I can't provide: I don't know whether it's OK to connect both Molex connectors to the same cable. The six pin PCI-E power connector is rated at 75W (6.25A at 12v). I guess that's more than a single Molex connector is supposed to provide.

Graphics card auxiliary power connectors (if required) MUST be connected for your system to work correctly. This connector supplies the GPU voltage regulator on the card in much the same way as the ATX 12V connector supplies power to the CPU voltage regulator on the motherboard. If your PSU already has a suitable connector, then it just needs plugging in. If, on the other hand, yours doesn't have this connector (and mine doesn't), then you need to use the adapter which came with the card. This has 2 molex connectors to provide power to a single PCI-E power connector. These molex connectors must be connected to SEPARATE power cables frrom the PSU and NOT to different connectors on the same cable. Ideally, there should be nothing else connected to any of the other connectors on the cables that you use for this purpose.

Thanks for the heads up Dwarf. I know that I have a connector around here somewhere in my boxes and boxes of cables. Just have to find it. I'll make sure, when I hook it up, to use molex connectors from different power cables.

Technically, you'd want to use 2 different 12v rails to power the adapter so that the power supply won't go overload on one 12v rail and trigger the safety. Since the OP's power supply is single rail design, it wouldn't matter which cable he use...

zzz2496