Can't enable SLI possibly because of different brands?

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skeedo

Senior member
Nov 29, 2004
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Have XFX 750i motherboard, MSI 8800GTS and Evga 8800GTS. I cannot get SLI option to show in nvidia cpanel. Tried swappin cards and bridge around, reinstalling drivers, yadda yadda. No option in Bios for SLI.

Is it the different brands that might be causing the problem? I believe the MSI card is clocked faster than the Evga, but I dont see why this would matter if they have the same GPU. :confused:
 
Apocalypse23

Apocalypse23

Golden Member
Jul 14, 2003
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skeedo said:
Have XFX 750i motherboard, MSI 8800GTS and Evga 8800GTS. I cannot get SLI option to show in nvidia cpanel. Tried swappin cards and bridge around, reinstalling drivers, yadda yadda. No option in Bios for SLI.

Is it the different brands that might be causing the problem? I believe the MSI card is clocked faster than the Evga, but I dont see why this would matter if they have the same GPU. :confused:
Click to expand...

You may have to set them clock for clock and try again. Overclock the Evga to MSI speeds and try, or downclock the MSI to Evga speeds.
 
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NoQuarter

Golden Member
Jan 1, 2001
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How much ram on the 8800GTS cards? The 320/640mb card has a different gpu than the 512MB card
 
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skeedo

Senior member
Nov 29, 2004
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Aw damn you're right...the Evga has 640mb ram and G80 gpu and MSI has 512mb with G92 gpu :(

Would flashing one of the bioses be a viable solution or just result in a piece of scrap metal?
 
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blanketyblank

Golden Member
Jan 23, 2007
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OCGuy said:
Yea they have to have the same amount of VRAM....
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It's not even about the vram in this case. These are totally different cards with different memory bus. Maybe you might be able to do something like flash a 640 to a 320 and SLI those (not that it would be a good idea), but different chips with different memory bus is almost impossible. Hell I don't think you can even SLI a 512 MB 8800 with a 9800 or 250 even though they both use g92 and are identical in almost everything.
Possibly BIOS flash might work there though.
 
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aka1nas

Diamond Member
Aug 30, 2001
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blanketyblank said:
It's not even about the vram in this case. These are totally different cards with different memory bus. Maybe you might be able to do something like flash a 640 to a 320 and SLI those (not that it would be a good idea), but different chips with different memory bus is almost impossible. Hell I don't think you can even SLI a 512 MB 8800 with a 9800 or 250 even though they both use g92 and are identical in almost everything.
Possibly BIOS flash might work there though.
Click to expand...

The SLI detection doesn't require the same amount of memory on each card, but it will use the lesser of the two cards due to the frame-buffer mirroring requirements of AFR. I don't recall offhand if you could mix the 320 and 640 MB 8800 GTS models out of the box.

The determination of whether SLI is available or not to enable is still done solely by model string, AFAIK. You can SLI cards with different numbers of cores w/o issue as long as they kept the model string as in the GTX 260s.

In the same vein, the 8800 GTX and Ultra cannot be SLI'ed together even though they are the exact same chip and only differ by default clock speeds because Nvidia changed the model string.

BIOS trickery can get around this, of course, but is not advisable if the cards are actually using different GPUs (G92 8800GTS vs G80 8800GTS).
 
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blanketyblank

Golden Member
Jan 23, 2007
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aka1nas said:
The SLI detection doesn't require the same amount of memory on each card, but it will use the lesser of the two cards due to the frame-buffer mirroring requirements of AFR. I don't recall offhand if you could mix the 320 and 640 MB 8800 GTS models out of the box.

The determination of whether SLI is available or not to enable is still done solely by model string, AFAIK. You can SLI cards with different numbers of cores w/o issue as long as they kept the model string as in the GTX 260s.

In the same vein, the 8800 GTX and Ultra cannot be SLI'ed together even though they are the exact same chip and only differ by default clock speeds because Nvidia changed the model string.

BIOS trickery can get around this, of course, but is not advisable if the cards are actually using different GPUs (G92 8800GTS vs G80 8800GTS).
Click to expand...

Yeh I never really liked the way NV did SLI when I had an NV card. You had to buy the exact same model. I was hoping to use SLI as a way to upgrade in the future so I was pissed when 9800 series came out with exact same chip and memory bus, but was SLI incompatible.
 
Keysplayr

Keysplayr

Elite Member
Jan 16, 2003
21,219
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It wont work. The 8800GTS640 is a G80 96 shader core, the 8800GTS512 is a G92 128 shader core. Very different cards in many aspects besides the example here.
No matter what you try flashing it to, which I do not recommend on a perfectly functional card.
 
nenforcer

nenforcer

Golden Member
Aug 26, 2008
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Sell the eVGA G80 8800GTS 640MB and get another 8800GTS 512MB for SLI. It would be worth it.
 
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blanketyblank

Golden Member
Jan 23, 2007
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I say sell both of them and get yourself a single better card. Better compatibility and lower power usage.
 
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DefRef

Diamond Member
Nov 9, 2000
4,041
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blanketyblank said:
Yeh I never really liked the way NV did SLI when I had an NV card. You had to buy the exact same model.
Click to expand...
When was this? I bought a BFG 8800GT OC 512MB and then a year later picked up a pair of PNY 8800GTs on clearance. I plugged in one of those next to the BFG and ran that for over a year before building my sig's rig and put the other PNY into the SLI and relegated the BFG to PhysX duty. (I'd pull it for my #2 rig and put an old 8800GTS 320 in, but my power supply is on the case bottom and the old card is a two-spacer. Yeesh.)
 
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NoQuarter

Golden Member
Jan 1, 2001
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DefRef said:
When was this? I bought a BFG 8800GT OC 512MB and then a year later picked up a pair of PNY 8800GTs on clearance. I plugged in one of those next to the BFG and ran that for over a year before building my sig's rig and put the other PNY into the SLI and relegated the BFG to PhysX duty. (I'd pull it for my #2 rig and put an old 8800GTS 320 in, but my power supply is on the case bottom and the old card is a two-spacer. Yeesh.)
Click to expand...

Well, they're both 8800GT's which is what he means by model.. ATI's Crossfire is a bit more lenient, you just need same family (5750+5770, 5850+5870) and it doesn't actually downscale the faster card to the slower (5750+5770 benches between 5750+5750 and 5770+5770)
 
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blanketyblank

Golden Member
Jan 23, 2007
1,149
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DefRef said:
When was this? I bought a BFG 8800GT OC 512MB and then a year later picked up a pair of PNY 8800GTs on clearance. I plugged in one of those next to the BFG and ran that for over a year before building my sig's rig and put the other PNY into the SLI and relegated the BFG to PhysX duty. (I'd pull it for my #2 rig and put an old 8800GTS 320 in, but my power supply is on the case bottom and the old card is a two-spacer. Yeesh.)
Click to expand...

I'm not talking about manufacturer overclocks or different manufacturers which are the same model with a different cooler(sometimes). I'm talking about different models by Nvidia (different name).
I had an 8800GTS 320 which I couldn't SLI since the new models were 512 (I don't think it was enabled for 640s either). I was OK with that since they were a different chip and had more memory so I sold the 320 and got a 512.
Then when I got a 8800 GTS 512, I couldn't SLI it with anything else but another 8800GTS 512 (see footnote in link below). That pissed me off because 8800GT, 9800GT, 9800GTX were nearly identical (same chip and same amount of memory) but I couldn't SLI with any of those.
I know there were 16 extra cores, but the minor performance benefit wasn't worth having my options cut off when I saw prices for the other cards drop was really annoying.

http://www.nvidia.com/page/geforce_8800.html
 
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aka1nas

Diamond Member
Aug 30, 2001
4,335
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NoQuarter said:
Well, they're both 8800GT's which is what he means by model.. ATI's Crossfire is a bit more lenient, you just need same family (5750+5770, 5850+5870) and it doesn't actually downscale the faster card to the slower (5750+5770 benches between 5750+5750 and 5770+5770)
Click to expand...

SLI doesn't downscale clockspeeds, either, unless you are playing with an overclock utility that doesn't let you clock the cards individually. It's only video memory where you get the lowest of the two, which I would imagine is also a limitation in Crossfire as I don't think they are doing anything much different than AFR.
 
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