My GTX590 is two 1.5 GB 580's on one card. It looks like both GPUs are running full bore when viewed in the control tool. Nevertheless, this card is slower in Clod than my single GPU 3 GB GTX580. IN SLI both GPUs are processing the same data so no benefit.
SKUD

However, two GTX 580's SLI beat a 590 by 15-20%. It actually has a tough time beating 2 GTX 570's. I believe the GTX 590 is underclocked at about the same as a GTX 480 for heat issues, which is why it is so quiet.

http://www.hardwarecanucks.com/forum...review-23.html

Working SLI in CoD would make a fair difference to the 590 because you cannot turn off SLI.

Agreed
I'm not certain whether the clock speed or the memory is the biggest contributor.

SKUD,
In Sli you don't double the ram of one card unfortunately, so your 590 (2x580's on one card @ 1.5gb V/ram) shouldn't give 3gb of ram only 1.5gb. The 580 with 3gb therefore is the reason of better performance. We will have to wait and see if the patch is going to address the V/ram issue. I have 2x1gb cards in Sli and both are working to full capacity indicated by my precision tool. I think at the moment V/ram or lack of it is some of the reason that those of us with 1gb are noticing more problems than those with 1.5gb or more. My frame rates are very good but the stutters down low are a pain.

Again agreed.
I believe if my 590 had 6GB (3GB each GPU) and same clock speed as my 580 it would get equal performance. Now the second GPU and the 1.5GB of memory it has is wasted. My precision tool also says both GPUs are going at it full bore. Trouble is I don't think they are splitting the work load, only doubling it. I believe SLI works by splitting the data stream sending half to each GPU and then recombining by interleaving the data after they have processed it. If the software isn't controlling that then both processors get all the data. Someone correct me if my perception is wrong.

Hi SKUD,

Interesting that you say that your precision tool shows both your cards working full bore, mine says the same. I have tried disabling one of my cards and that shows zero use on the V/mem on that, and the fps drops to about 60% of what I get with both cards working but the V/mem still shows near max use on the working card. I have my clocks and voltages set to the same for each card even though they are from different stables and the percentage of use on each card only varies about 2% from one card to the other, that also varies with one card using more, then the other. Temps on both cards are within about 2--3deg of each other with card 2 always slightly lower than card 1 (this is what information I get from the different makers, the EVGA slightly hotter running than the Asus) and both are within the 50--60deg range. I wonder if others using Sli are getting the same results, it would be interesting to find out.

I have 2x GTX 580 3gb (disabled SLI for CoD). I never come close to using the 3 Gb with CoD and I use 2650 x 1600 res on an SSD (helped slightly but not much). I believe just over 2 Gb vRAM is the max I have ever used. My GPU and CPU are never maxed out, and my RAM is never maxed out but the stutters are really a problem especially low or over cities. Proof the stutters are not from a lack of resources at least on my rig.

more rendering=more interop...more interop=more stutters :(

Could you please expand your explanation. Thanks.

Icarus,

Thanks for your information, from what you have said it looks like lack of V/mem isn't the cause of stutters with CoD that a lot of us are getting. My two cards are only 1gb each and with CoD they are both using between 990mb--1007mb each (cards @1024mb each), no other games that I have come anywhere near this. RoF is using under 75% on each card, so I'm hoping the patch will address CoD's V/mem demand.