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SLI Woes!

ludicrousgib

ludicrousgib

ludicrousgib

Associate
Joined
6 Jul 2013
Posts
36
Hi folks, Hopefully someone can help/suggest something.

I recently aquired 2 new GTX 670 cards, to sit in a z87 deluxe mobo.

Install was fine, and off I went, happy with the performance as this was a quite a large step forward from my previous rig.

It was only recently, whilst playing around with lightboost, that I wanted to see what actual performance I was getting, and whilst the results werent bad, they just werent what I was expecting.

After a bit of testing, It seems that I am only using one of the 670 cards. Afterburner reports 1 cards usage varying, task dependant, whilst the other is constantly stuck at 30 or 31%, either on the desktop or in game. It doesnt move.

Running the Valley benchmark shows a similar story, showing clock speeds etc for one card being high, the other extremley low.

Having looked on Nvidia COntrol Panel, there are no options anywhere relating to SLI. I have tried numerous different driver versions, all with the same results.

I have tried both cards individually, and both work fine.

Both the cards are displayed without error in device manager, and both cards are displayed in the nvidia control panel, there is just no option to enable SLI. It appears at the moment, that one card is being dedicated to graphics, the other to physx. The only option I have is so change Physx to the CPU. This still only results in one card being assigned to graphics.

I have looked through my bios, but cannot see anything obvious relating to SLI being enabled/disabled.

The only piece of the puzzle I cannot test is the SLI bridge, as I dont have a replacement, though, I am under the impression SLI would work regardless of a bridge being present or not - just with very reduced performance.

I am at a complete loss as to where to turn.

Would greatly appreciate any help.


Thanks.
 
ludicrousgib said:
I am under the impression SLI would work regardless of a bridge being present or not - just with very reduced performance.
Click to expand...

It's been a while since I last used SLi, so I'll leave it to those that know better to help you on this one, but I can tell you SLi won't work at all without an SLi bridge and there is an option to enable SLi when everything is in working order.

It would be better if you put in your full specs too, so that the SLi gang will be able to help you better.
 
Yeah you need the bridge, could be a faulty one as to why it's not showing the option but I'm not 100% on that. They're not exactly sturdy things so could easily break.
 
Deceptor said:
Yeah you need the bridge, could be a faulty one as to why it's not showing the option but I'm not 100% on that. They're not exactly sturdy things so could easily break.
Click to expand...

Thanks for the replies.

FWIW I may aswell try another bridge as they arent expensive at all, just I had read that SLI would work without one, but with something like 50% less performance.

Anyway, I'll see if I can find one somewhere today and report back.

Cheers.
 
When enabling sli it should look like this in the control panel, just scroll down a little in the link to the control panel pic.

http://www.maximumpc.com/article/features/sli_vs_crossfire_which_dual-card_setup_best

To enable click on maximise 3D performance.

You have to enable SLI in control panel as the default off, also whenever you update graphics driver you have to enable it again as it will always default to off.

Hope your new SLI bridge solves the probs.
 
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Mine doesnt look anything liek that.

At the bottom it has both cards, but no green bar with SLI.

It has no SLI configuration options like maximise 3d / disable.

On the menu on the left it doesnt refer to SLI, just physx (iirc at work)


Each card works fine on its own in either pcie slot, and windows/nvidia cp/gpu-z detect both fine, so its not the cards, or the pcie slots.

It screams driver issue to me, but having chosen half a dozen different drivers, none of them work.

I really have my doubts about the sli bridge, but its worth a bash.
 
ludicrousgib said:
Mine doesnt look anything liek that.

At the bottom it has both cards, but no green bar with SLI.

It has no SLI configuration options like maximise 3d / disable.

On the menu on the left it doesnt refer to SLI, just physx (iirc at work)


Each card works fine on its own in either pcie slot, and windows/nvidia cp/gpu-z detect both fine, so its not the cards, or the pcie slots.

It screams driver issue to me, but having chosen half a dozen different drivers, none of them work.

I really have my doubts about the sli bridge, but its worth a bash.
Click to expand...

If both cards are fine as you say in either pci-e slot then the bridge must be at fault, you will see those options in control panel once your cards are set up correctly
 
Run heaven with sli disabled and then with it enabled again, or run a fps game like bf3 with the same test.

You should see your fps / scores increase by at least 75%
 
ludicrousgib said:
Thanks for the replies.

FWIW I may aswell try another bridge as they arent expensive at all, just I had read that SLI would work without one, but with something like 50% less performance.

Anyway, I'll see if I can find one somewhere today and report back.

Cheers.
Click to expand...

There was a time when low end nVidia cards would run in SLI without a bridge but that is no longer the case.

Did you actually have a bridge when you first reported this issue?


Andi.

BTW what did you have before the 670's as a video card.
 
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I have a bridge which is connected, but its the only piece of the puzzle which I havent tested. I'll wizz to my local pc shop and see if they have one knocking about.

I previously had a 6850 in a different machine
 
Believe it or not it's possible to connect a SLI bridge upside down and when you do problems such as yours can occur.Also are both cards the same vram sizes? i.e 2x2gb or 2x4gb? done bios update too?
 
The control panel you are describing is exactly what you would see with two cards installed without the bridge connected so it is hopeful you may just have a faulty bridge connector. Let us know how you get on.
 
Sycho said:
Believe it or not it's possible to connect a SLI bridge upside down and when you do problems such as yours can occur.Also are both cards the same vram sizes? i.e 2x2gb or 2x4gb? done bios update too?
Click to expand...

Theyre both identical brands - I havent done any bios updates... which did niggle me slightly at the back of my head, although again, dont imagine thats the case.

Didnt realise you could install a bridge the wrong way round, as it doesnt have a nipple (lol, only word i could think of :/) to ensure it goes in the correct way. I have taken the bridge off to check the cards, but couldnt say if i put it back on the same way around or not. SOmething else to try I guess.

spankingtexan said:
The control panel you are describing is exactly what you would see with two cards installed without the bridge connected so it is hopeful you may just have a faulty bridge connector. Let us know how you get on.
Click to expand...

This does sound promising then. I will hopefully be able to give this a try at lunch time, providing my local shop has one knocking about, if not will have to wait on delivery.
 
i remember having the same issue a couple of years back....uninstall drivers clear from registry.. start again. make sure the bridge is sitting ok. install drivers for both cards with the same drivers.. it took me a few times to get it working right.. not sure if this will help... i tried about everything at the time... eventually got it to work!.
 
Unfortunately a new bridge hasnt changed anything. I tried the bridge both way rounds, on both bridge ports.

I have now completley run out of ideas, other than a windows reinstall, although realistically wouldnt see that achieving anything.
 
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