Does a GPU used as dedicated physx consume less power than as primary?

I've been thinking of installing my gtx 280 as a dedicated physx card to help the gtx 580. The question is will the 280 still consume it's TDP doing physx, or will it consume less than full power? This is to know if my PSU can take it.

 

Yes it does use less as physx,a guess from own measures id say 60-70% within tdp.Couldnt say if it would work with your psu,but you could make a nice undervolted bios for the 280,would probably help fannoise too,goes for cpu as well,dunno bout 580 and its throttling vs volts

 

it depends on the actual GPU load....which will vary based on the physx effects used. If the card is placed under full load....it doesn't matter whether it's processing physx or graphics data, it will draw the same amount of power.

 

+1 to this...

 

with a dedicated 8800gts phys and gtx460,i went through whats worth trying with physx recently,none nearly maxed the gpu looking at the wattmeter.So not saying your wrong,but when it comes to todays games,no way his gtx280 will be maxed.

 

If you look at the effects used in "today's games" compared to the full SDK.....you're right. But, in that freak occurance that some company decides to actually make full use of the PhysX SDK....his GTX280 can easily be maxed. The OP asked if his GTX280 will consume it's full TDP doing PhysX....and the only accurate answer is "Yes". My GTX460, with 336 Shaders (compared to 240 Shaders of the GTX280) reaches 72% usage in 3DMark Vantage's PhysX test (CPU Test 2). That test is more demanding than any game and would put the GTX280 near it's full TDP. Eventually, games will be as demanding.

 

Thanks to all, that was very informative!
Actually I figured out it won't matter even if the 280 will be maxed out, as to my calculations the seasonic x-750 gold will cope with the load. At full TDP(unlikely) the gtx 280(236w) and gtx 580 (340w -just to exaggerate),the system will still consume no more than 700w(according to reviews of 280 sli and 580 sli). While the PSU can easily give the equivalent of 840w, let alone 750w.
BTW, 12v rail amps= 62A.
But I'm still looking into it before I go ahead...rogram:

 

Your PSU won't survive trying to deliver 840watt continuously....and the GTX580 doesn't consume 340watts.....it's TDP is only 244watts.

 

the GTX580 WILL do 350w unlocked!

http://www.geeks3d.com/20101115/geforce-gtx-580-unlocked-350w-under-furmark-thanks-to-gpu-z/

 

Outside of it's stock settings, it doesn't comply with the PCIe 2.x spec....which gives a 300watt maximum power draw.