dedicated physx card

[Okedokey]

Im not talking about efficiency Im talking about power consumption. If your power supply is consuming more power at a 40% load than at a 90% load there is a problem. I have no issue believing its more efficient at 90% than 40%, as yes most PSUs are that way, however I have a hard time believing that its consuming more power at 40% than 90%.

Your defense to me saying that your 580 is just consuming more power was to say that your PSU consumed more power without the added 580. By claiming that its not increasing your electric bill your saying that your PSU is consuming equal or less power from the wall to produce that extra 200w or whatever needed which I just find hard to believe.

Wow dude, where to start... and please stop...

You've completely derailed this thread with your ignorance.

Back to the OP's question.

Xmorpheus, this mate

Yes it would help. The CUDA cores on the quad 690 sli would be freed up for Physx used on the 680, but as I said in previous post, you may be offsetting that performance increase by the reduction in PCIe lanes that you're limited to with a 2700K. Additionally, your PSU is already near capacity so it would not be a good idea.

The only way to tell would be to download 3DMark11 (which uses physx)

Run it the following benches 3 times and get the average:

1. 2700K dedicated to Physx - 1 GTX 690
2. 2700K dedicated to Physx - 2 x GTX 690 quad SLI
3. 2700K - 1 x GTX 690 dedicated to PhysX, 1 x GTX 690 not in SLI.
4. 2700K - 2 x GTX 690 quad SLI - 1 x GTX 680 dedicated to physx.

Post score from those runs (run them each 3 times and average the results).

BUT! If you have a watt meter or a multimeter to test the 12V rail, because without a doubt, 5 x 680 cores will max that PSU. I would want to see you put an additional Corsair 450W PSU to run the mobo as although this is marketed as a single rail PSU, its, not, it has 4 x 12 Vrails with OCP which may make it shut down if you added the GTX 680 so be careful.

My guess is that your loss of PCIe lanes will outweigh the physx component and your scaling in real world gaming will be terrible. My guess (if you do the bench) is around 30% loss in performance due to PCIe lanes (8x rather than 16x) vs about 15% increase due to physx in the games that support it and benchmarks. So I expect a 15% reduction in performance between 2 and 4.

That is however with the disclaimer around the PSU.