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Trellot · Tue Aug 22, 2006 4:01 pm

I sent in system information on Valve's Steam network and it came back not being able to detect SLI or Crossfire. Well I have two 7800 GTs installed and there doesn't seem to be any problems...however when I check Direct X it indicates that only one card is present...what gives...am I not running in SLI? Is there a BIOS process I need to enable or something on the MB like a jumper...you'd think if it wasn't running in SLI that there would be an error due to the extra VC! Any suggestions would be great!

Trellot

keshman87 · Tue Aug 22, 2006 4:31 pm

IIRC theres an option in the nvidia control panel to enable sli. check that out

Trellot · Wed Aug 23, 2006 2:56 am

I'm reading where the control panel for the eVGA video cards says the following for enabling SLI:

You must remove any graphics cards that are not compatible with NVIDIA Scalable Link Interface (SLI) technology before you can enable SLI

My cards are 7800GT eVGA video cards, both of which are certified SLI? What gives? Like I was saying before, if something is not right wouldn't the extra card cause problems since my system is only detecting one?

Any suggestions?

Trellot

Shintai · Wed Aug 23, 2006 3:41 am

Sounds like your SLI aint working at all. Is the cards running at the same speed, do you see the second card in the device manager?

Stripe7 · Wed Aug 23, 2006 4:09 am

It is easy to tell if SLI is working on your system, turn on the show GPU load balancing.

DxDiag does not report 2 cards on my system and I know SLI works on it. When I turn on the GPU load balancing I can see the green line which demarks where the break is between the two cards. That is one card handles the top half of the screen and the other the bottom half.

Severus · Wed Aug 23, 2006 5:15 am

I went through this initially when adding a second 7800GT to my rig - the second card wouldn't detect (and therefore didn't show up in Device Manger), then after endless reboots did detect, but wouldn't allow me to enable SLI with the same "remove incompatible adapters" message you're getting.

Its hard to remember but I seem to recall removing one adapter, resetting the SLI flip-card to single card mode, booting back up, shutting down, flipping back to dual card mode, booting up, shutting back down, then adding the second card.

Then it was all gold. I've done a rebuild since when I moved to the raptors and have had no problems on the new install. I think its just old installs that had a single card that get freaked when a new one is added.

EDIT - I wouldn't trust the GPU load balancing info very much, BTW

In SIN Episodes I get just under double the framerate with SLI enabled but GPU load balancing always gives one card the bottom 5% of the screen and the other card the remaining 95%. I don't think its particularly (or at all?) accurate.

lordT · Wed Aug 23, 2006 5:16 am

See whether you have SLI enabled in the Nvidia cpanel

Severus · Wed Aug 23, 2006 5:18 am

lordtottuu wrote:
See whether you have SLI enabled in the Nvidia cpanel

Yeah, he's not being allowed to enable SLI because it thinks he has a non-SLI capable card installed.

Trellot · Wed Aug 23, 2006 7:12 pm

Ok...I will take the extra card out and boot up with only one card, then I will add the second card and then maybe it will detect. I built my current system completely fresh, with a clean raptor drive and clean new XP install and I had all my components, including my cards in SLI mode, already installed and ready to go. So, maybe I should have started with just one card, then added the other one later? I think I remember asking about this before building my rig and that was the response I got...don't know why I didn't do it

!

I'll let everyone know what happens.

Thanks,

Trellot :roll:

Trellot · Thu Aug 24, 2006 3:25 pm

Well, I removed one card and then booted up my system and It acted just like it does normally. Then I powered down, added the second card, then booted up and it acted just like it does NORMALLY. Which is to say, that it's still not detecting the second card. In fact, I plugged my monitor into the second card on this last boot up and my monitor remained black as if it weren't plugged into anything! What do I do now, boot up with the card that isn't being detected to see if something is wrong with it? I'll do that now. I hope nothing is wrong with one of these cards...I spent 300 smackers in each one...heh. :-?

Trellot

Trellot · Thu Aug 24, 2006 7:01 pm

Ok...I placed each graphics card, one-by-one, in each of of the PCI-E slots and the computer acknowledged them without any problems each time...also, the eVGA Control Panel said under SLI that the cards were SLI capable and recommended that I install a second card to increase my graphics performance. So, then I install both cards with the SLI bridge attached and the Control Panel goes back to saying I should remove any non-SLI graphics cards in order to enable SLI capability?! Is my SLI bridge bad or something? Or might there be something in my BIOS to enable or disable? This is strange...oh, also, when both cards are installed my monitor won't work on the second card in either DVI plug...it only works on the first installed card.

What now?

Trellot :-?

Thu Aug 24, 2006 7:03 pm

There should be some switch on the motherboard too?

Hance · Thu Aug 24, 2006 7:24 pm

I will take a stab at your problem . I built a system for a friend of mine that had the exact same issue that you describe . after lots of cussing i figured out that the little SLI flip card thingy was bad . your motherboard should run 16+1 or SLI mode . so give this a try . put the sli card in the motherboard in 16+1 mode and put one of your video cards in the slot that is the 1X PCI-E slot ( probably the bottom slot ) . Performace would be terrible but it proves that the slot is working . Now if that works flip the card over to SLI mode and try to boot up with the card in the bottom slot again . If it doesnt work odds are your flippy card thingy is bad . It took me 6 hours and enough cuss words to make George Carlin blush to figure it out . EPOX put a card in the mail after i explained the problem to them.

Severus · Thu Aug 24, 2006 7:32 pm

Yar, also make sure you clean the contacts on the SLI card, there are reports that it fixes the issue on the A8N-SLI - rub a pencil eraser along the gold fingers.

Trellot · Thu Aug 24, 2006 8:47 pm

What is this SLI "Flip-Card" people are talking about? I have an SLI bridge to connect both cards...is that it? Otherwise, if it's something on the motherboard, my LanParty Expert board is supposed to auto-detect single or dual video cards without any jumpers or whatnot. Not sure what is meant by "flip-card".

Trellot

Severus · Thu Aug 24, 2006 8:55 pm

I thought the SLI DR had a huge bank of jumpers for enabling SLI mode?

SNM · Thu Aug 24, 2006 9:29 pm

Severus wrote:
I thought the SLI DR had a huge bank of jumpers for enabling SLI mode?

The Expert is a newer version and not the same as the original SLI-DR. I have no idea if it autodetects or requires jumpers, though.

Trellot · Fri Aug 25, 2006 12:15 am

I purchased the Expert based on this feature of auto-detection, so I hope I'm not going crazy, heh.

Anyway, I will try these troubleshooting methods you all have proposed to see what gives. Thanks a bunch!

Trellot :-?

Trellot · Fri Aug 25, 2006 2:46 pm

So I checked my BIOS settings and it is set at 2-1-1-16 for the slot setup and I enabled the SLI Aperture spread feature...or something like that. Now the eVGA Control Panel detects both cards by saying 7800 GT and 7800 GT (2), but the SLI feature under both cards still says that I need to unplug any non-SLI cards! I also cleaned the SLI-bridge contacts on the video cards with an eraser, but without success.

Do you think the SLI Bridge connector that came with the motherboard is malfunctioning? On another note, if both cards are being deteced, both in Control Panel, and in the eVGA Control Panel does that mean I'm running in SLI?

Thanks for any suggestions,

Trellot

JoshMST · Fri Aug 25, 2006 3:26 pm

What drivers are you using? If you are using the drivers from the EVGA install disk, I would recommend just going to get the latest NVIDIA reference drivers and doing it that way. EVGA could be bundling some very old drivers on their disks.

Trellot · Fri Aug 25, 2006 3:41 pm

I've updated the drivers on Nvidia's website, so they're all up-to-date. It must be that darn SLI bridge connector...sigh.

Trellot :-?

JoshMST · Fri Aug 25, 2006 3:48 pm

Shouldn't the PCI-E slots be set for 8-1-1-8? 2-1-1-16 makes it look like there is on x16 slot, while the other card sits in the x2 slot. I wonder if NVIDIA's drivers disable the second card if it isn't plugged into a x8 or x16 slot for SLI?

Evil Engine Number Nine · Fri Aug 25, 2006 3:51 pm

SLI should still work without the bridge connector, just not as well. So that probably isn't your problem. you have the NVIDIA 91.31 series drivers? Did you also update your chipset driver for you MOBO?

Evil Engine Number Nine · Fri Aug 25, 2006 3:54 pm

PS: do you have both cards plugged into the PSU with the 6pin/12volt's?

Trellot · Fri Aug 25, 2006 8:03 pm

Yes, both cards are plugged into the PSU, I'll have to check on the Driver version, and no I don't think I've updated my chipset drivers so I'll definitely try that when I get home from work. The 2-1-1-16 is the only other option, the other is something like 8-1-NC-8, so I didn't think that would be right.

Trellot

Forge · Fri Aug 25, 2006 8:46 pm

8-1-NC-8 is exactly the right setting. You need to have both graphics cards getting as much bandwidth as possible. IME, running 16/4X is roughly the same as 4/4X, whereas 8/8X gives 8/8X. Probably a sync issue, where the slower card still has to sync with the other and thus limits the usable PCIe bandwidth.

2X isn't a PCIe standard setup, FWIW, that might be too little for the GPU to properly initialize.

My DFI NF4 SLI Infinity just runs 8/8X all the time, FWIW.

Trellot · Sat Aug 26, 2006 3:26 pm

Yes! I got SLI running! It was the drivers for the video cards...91.31 version. I updated the drivers recently, but this was altogether a newer version. So, now my DirectX is reporting only one card instead of two, which is good becuase they're SLI'd, although I wonder why it doesn't add up the ram to 512, instead it still reads 256..hmm, oh well.

Thanks for all the support, and on the last post, then I suppose I will go back and set the BIOS to 8-1-NC-8 and see what I get in performance. Thanks all!

Trellot

Trellot · Sat Aug 26, 2006 4:03 pm

Forge wrote:
8-1-NC-8 is exactly the right setting. You need to have both graphics cards getting as much bandwidth as possible. IME, running 16/4X is roughly the same as 4/4X, whereas 8/8X gives 8/8X. Probably a sync issue, where the slower card still has to sync with the other and thus limits the usable PCIe bandwidth.

2X isn't a PCIe standard setup, FWIW, that might be too little for the GPU to properly initialize.

My DFI NF4 SLI Infinity just runs 8/8X all the time, FWIW.

K, so I set this option and my screen went black. I had to reset my CMOS batt to clear the settings. I guess 2-1-1-16 is the right one, 'less I'm doing something wrong.

Trellot

Severus · Sat Aug 26, 2006 11:20 pm

There should definitely be 8 lanes for each card, so you still have something b0rked

Use RivaTuner to check the number of lanes being allocated to each card. It should report something like 16x physical 8x electrical or something along those lines if memory serves.

Oh, FWIW, I just remembered that I had to flash the BIOS of both cards to be the same (even though the new drivers supposedly remove that requirement) and took the opportunity to do some BIOS-level overclocking and the BIOS volt mod for 7800GTs while I was at it

Choz · Mon Aug 28, 2006 1:35 am

Out of curiousity are you're 2x 7800GT's from exactly the same series? I once had a problem in that 2x 6600GT's were from the same manufacturer but different revisions so they would not work in SLI. The store I got them from was forced to replace my 6 month old one with a brand new one as SLI was a promised feature.

BTW you won't get a reported 512MB with 2x 256MB cards in SLI because each card uses it's own ram and doesn't share.

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