SLI Performance worse than with one card

[Michaeljcox24]

Two cards: Superoverclock 580 and Gigabyte OC Winforce 580

When I SLI them, on a 1050W Corsair PSU, Heaven max frame rate is 60

WHen I run either card on it's own, max frame rate is 125 odd

What could be causing this? Any ideas lads, I'm stumped.

 

[Diablo]

Check that when it goes into SLI there isn't some random setting for Vsync (as this would probably cut down on stutter), but would limit frames to 60fps.

 

[Michaeljcox24]

I've checked, and Vsync is already disabled in nvidia control panel and also in the application itself.

 

[Michaeljcox24]

Since my last post ive deternined it was msi afterburner doing something to the clocks on the cards which made them massively underperform. However, now im stuck in the situation where i dont have anything to monitor temps in an osd and stuck for changing voltages. any ideas lads?

 

[yassarikhan786]

Why don't you use HWMonitor or the OC3D HWMonitor to check GPU temps and voltages?

 

[Michaeljcox24]

I thought HW Monitor only did CPU temps.

Just had a thought while I was doing a job at work. I wonder if the problem has been caused by having the faster card in the primary slot? Theoretically, the slower card should be clocked up to the speed of the superoverclock but if the stock voltage isn't enough then it would crash (which I have been observing)

It wouldn't cause horrible performance (well, logically, it shouldn't do) but until I've run the slower card in the primary slot, I can't rule that out.

Will try tonight.

 

[yassarikhan786]

It shows GPU temps/voltages as well.

 

[Michaeljcox24]

Does it have an OSD so you can watch in game like afterburner does?

 

[yassarikhan786]

Does it have an OSD so you can watch in game like afterburner does?

It doesn't as far as I know.

 

[Michaeljcox24]

Any idea which one does?

 

[SnW]

http://www.fraps.com/

 

[yassarikhan786]

I have fraps, but it doesn't show temperatures does it? I've not used it for a while so I don't know tbh.

 

[Michaeljcox24]

I thought fraps only did what it said on the tin i.e frames per second

 

[SnW]

I have fraps, but it doesn't show temperatures does it? I've not used it for a while so I don't know tbh.

O oops, i am totally focused on FPS , my bad !

 

[Scoob]

Just had a thought while I was doing a job at work. I wonder if the problem has been caused by having the faster card in the primary slot? Theoretically, the slower card should be clocked up to the speed of the superoverclock but if the stock voltage isn't enough then it would crash (which I have been observing)

Hi,

This shouldn't make any difference. In fact, contrary to what a lot of people may think, a pair of different-clocked NV cards can happily work together. For example, while benching my pair of GTX 570's I noticed the GPU load on one was consistantly 3-5% LOWER than the other, suggesting SLI wasn't balancing the load quite as well as usual. Anyway, it turned out that MSI Afterburner had only applied my OC profile to ONE of the cards, the faster card having to work less to keep up with the stock card.

I don't think it's a good idea to run at different clocks as the OC'd card is in effect waiting for the slower card, but it does work fine.

There is a new Beta of afterburner (beta 12) available, maybe that would work better for you? I'm using beta 10 currently and it's fine with my 570's. Only Skyrim shows poor (zero!) SLI Scaling but that's Skyrim for you, Heaven basically gets a near 2x boost from ~45fps single card to 85fps for the pair (@ 1920x1200)

Cheers,

Scoob.

 

[exaisle]

Not sure if this will help (I didn't read everything here) but my 6970s ran worse in crossfire than non crossfire at first. Here the simple fix was to download the "application profiles" driver from the amd website. Perhaps Nvidia has a similar option on their site?

 

[Michaeljcox24]

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

 

[yassarikhan786]

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

Nice. So what was the scaling like?

 

[Michaeljcox24]

Didnt record any data mate wednesdays is the night i go for a chicken tikka with the missis. hopefully will be able to get some data tonight and post.

 

[yassarikhan786]

Didnt record any data mate wednesdays is the night i go for a chicken tikka with the missis. hopefully will be able to get some data tonight and post.

Cool, thanks. I bet you were relieved

. Did you notice any stuttering in the short while that you had the cards running?