SLI Performance worse than with one card

[Michaeljcox24]

No tbh never noticed any mate

 

[yassarikhan786]

That's good

.

 

[Scoob]

Lads,

Last night I swapped the cards over so the normal OC Windforce card was in the primary slot with the SOC below it. Performance was massively improved in heaven bench, and what you would expect from SLI'd 580's.

So for future reference, if anyone comes across a similar thread, to enable proper functionality in Afterburner in SLI you MUST run the slower card in the top slot otherwise the cards massively underperform.

Thanks for the suggestions

Hi,

Glad you've fixed it, however the "fix" is rather...unexpected.

I was running my 570's with just the LOWER card being overclocked to 850, whereas the upper was 732 and SLI worked just fine. Ok, as I mentioned previously, the lower card reported a lower % load as you'd expect but I certainly had the very healthy FPS boost you expect SLI to provide.

I wonder if what you've encountered is some weird quirk of your particular combination of hardware, either way it's good information that may help others.

I admit, I was surprised my two 570's ran flawlessly despite their vastly different core clock speeds. Both are now at 850 as I originally intended and load is balanced near perfectly. While my cards were running fine with a 118mhz core speed difference, natively they are both stock-clocked cards, so 732mhz - maybe that's the difference, your cards having different stock settings.

I am actually tempted to swap my cards over anyway as my upper card has an older, and less effective, cooler than the lower (newer) one, so it may help things.

Cheers,

Scoob.

 

[Michaeljcox24]

Results

Taking the voltage up to 1.1V, which is the max I tended to go on my SOC, the highest I could get the OC Special edition up to was up to 840, which when your used to an SOC up at 950, is a kick in the gonads to be honest. I hate the damn silicon lottery. Anyway...

580 Overclock Special Edition on it's own @ 840 (heaven stock settings)

Heaven Score = 1250

Max FPS = 113.5

Max Temp on Card = 63C

580 SOC and Overclock Special Edition in SLI @ 840

Heaven Score = 2492

Max FPS = 240.8

Max Temp Top Card 75

Max Temp Bottom Card 70

So yeah, pretty much twice the performance. Anything less, I would have been a bit annoyed with I guess. In hindsight, I wish I had gone with an SOC for the 2nd card, but there were none available at the time in the shop. Seen some on Amazon though, but not quite sure how higher a score the SOC gets compared to the standard.

Either way, when you get to that high level of performance, everything is just numbers. I know I wouldn't see poor performance, it's just not perfection, and when you spend the amount of money I have, nothing short of perfection will do!

I wonder if TTL will sell me his SOC....

Most impressive of all to me, is the temperatures I achieved. My case is a HAF-X, and yeah, people say it's big and ugly, but with the special ducting on the side and a 200mm megaflow on full blast, those are dam good temps for SLI on air. To give you an idea, without the side on the case, temps go up to 89-90 after 5 mins of heaven.

Just for peace of mind, I might try running the SOC on it's own at 950 to see how much performance I'm missing out on.

 

[yassarikhan786]

I'm really impressed with your results mate and especially the temps.

 

[Michaeljcox24]

Thanks, I was also quite chuffed with the temps myself and might even go out for a beer to celebrate

 

[yassarikhan786]

Thanks, I was also quite chuffed with the temps myself and might even go out for a beer to celebrate

lol, you deserve it man.