16x vs. 8x for SLI

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devman

2[H]4U
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Dec 3, 2005
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Is it going to be a problem that my NF41 mobo uses 8x PCIe slots for SLI mode instead of 16x? I'm thinking of doing 2x 8800 GTS 640 (G80) or 2x 8800GT 512 (G92)
 
No it won't be a problem, 2 slots operating at 8x times two = 16x. It's just the way it works and it will be fine.
 
The difference is pretty much only noticable in benchmarks. I don't know how it is with 8 series cards, but even using 7950GX2 cards on such a board only results a frame or two being lost from running dual 8x instead of dual 16x.
 
FWIW i definately noticed a difference when i ran my abit 650i 8x8x board compared to my 680i 16x16x board.
 
veedubfreak said:
FWIW i definately noticed a difference when i ran my abit 650i 8x8x board compared to my 680i 16x16x board.
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You were using 8800 series cards though, weren't you? How much of a difference was it, because in June I'm upgrading to an E8500 and still not sure which board to get for SLI...
 
Well i bought the abit fatal1ty 650i board because i needed to get my rig back up and running while my 680i was in RMA. So i went from running 8800GT's in SLI on the 680i, to running my SLI GTS512 setup on the 650i (my board burned up the day after i ordered the GTS's :( )My GTS setup on the 650i setup scored lower than the GT setup did.

At this point, if you are buying a new SLI board, just get a 780i, no point in cheaping out on the motherboard.
 
veedubfreak said:
Well i bought the abit fatal1ty 650i board because i needed to get my rig back up and running while my 680i was in RMA. So i went from running 8800GT's in SLI on the 680i, to running my SLI GTS512 setup on the 650i (my board burned up the day after i ordered the GTS's :( )My GTS setup on the 650i setup scored lower than the GT setup did.
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You scored lower; did you notice much difference in action gameplay though? 3DMark is very rarely a good indicator of actual performance.
 
I didnt notice a huge jump in gaming performance with my Asus 650i board from 8800GT to SLIed GT's Resolution was only 1680x1050 but with 4xAA/16xAF. 3dmark went up maybe 1500 points though.
 
Its hard to notice any difference in games, because even with the 650i and SLI'd GT cards theres not really much out there than can bog them down. But yes, i can definately see the difference in crysis between the 650 and 680.
 
But SLI'd GTs will still be better than single G80 GTS 640, even on an 8x 8x board right? (nForce 4 if that matters).
 
Well that is making me think twice about a 650i board. Isn't the 750i SLI supposed to have two 16x slots? I'm certainly NOT paying $300 for a motherboard...
 
650i is two 8x PCI-E 1.1 slots (when in SLI mode). 750i is one 16x and the other 8x, all the time. And they're PCI-E 2.0 slots, so a 8x slot there is like a 16x slot on an earlier board, as long as you have PCI-E 2.0 graphics cards to plug in there. If you don't need more than two 16x-wide slots and have PCI-E 2.0 video cards, I don't even see a reason to get a 780i over a 750i anymore.
 
veedubfreak said:
Its hard to notice any difference in games, because even with the 650i and SLI'd GT cards theres not really much out there than can bog them down. But yes, i can definately see the difference in crysis between the 650 and 680.
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How much of a difference in fps do you think it made? Just curious, I haven't been able to get a definitive answer for whether the 8800GT in sli would actually require and/or use the bandwidth provided by 16x/16x.
 
It could also be that the Abit 650i board i has was just a huge hunk of shit. It wouldnt overclock at all. Personally i think the extra features you get with the 680i are worth the extra money.
 
veedubfreak said:
It could also be that the Abit 650i board i has was just a huge hunk of shit. It wouldnt overclock at all. Personally i think the extra features you get with the 680i are worth the extra money.
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I've never needed more features than what my MSI P6N Sli provides. It runs SLI at 8x8.
 
I had both an eVGA 8800GTS 640mb Superclocked and an eVGA 8800GTS 640mb SSC SLIed on my Asus A8N-SLI (first-gen SLI, drops down to 8x while in SLI, DDR, nForce 4 mobo) and I just never got the performance I should have gotten- I was seeing some small to moderate framerate boosts, but that didn't translate to extra AA or higher settings, which is contrary to what I expected and what I'd seen as far as what I should have gotten. I'm certain I was not cpu-bottlenecked and did enough testing to pin the problem on the mobo (had plenty of power, I might add). I don't know if it was necessarily the PCI-E slots dropping to 8x, the DDR, or just the fact that it was a first generation SLI board- whatever it was, it just didn't work well, so I sold-off my older card (the 8800GTS 640mb Superclocked). I was thinking of stepping-up to a 9800GX2 now from the 8800GTS SSC, but besides from the fact that it looks like the 9800GX2 won't even hit my window now, the $600 price tag is way too much for that thing. Anyway, I guess I'm fine for now- the mobo runs my single 8800GTS SSC perfectly fine and my performance does match-up with the testing I've seen done by others and review sites like [H]. Besides Crysis, UT3 is probably the only other game where I'd like just a little, really just a tiny bit, more performance (could maybe OC that out of it, but this is stock-OCed as-is; I'll look into it though now that I know the 9800GX2 isn't coming my way).
 
I wonder if benchmarking SLI is just that: benchmarking. You get great 3dmark scores and framerates on games, but that does not tell you the whole story. UT3 for example gets higher framerates with my SLI 9600GT setup than with a single card. However, the experience while playing is not smooth at all. Too jerky. I'd much rather play with a single card than with SLI. Same thing with some of my other games like TOCA Race driver 3. CPU is not a bottleneck with E6400 @3.4ghz
 
ScourggeFX said:
I wonder if benchmarking SLI is just that: benchmarking. You get great 3dmark scores and framerates on games, but that does not tell you the whole story. UT3 for example gets higher framerates with my SLI 9600GT setup than with a single card. However, the experience while playing is not smooth at all. Too jerky. I'd much rather play with a single card than with SLI. Same thing with some of my other games like TOCA Race driver 3. CPU is not a bottleneck with E6400 @3.4ghz
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Very true. Oblivion is very jerky with SLI'd 7800GTXs, a single one plays better imo.
 
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