real world disadvantage of running 2 gtx 275 sli in 8x vs 16x

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hollandbk

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me and a friend who is building a 1156 system ( and is thus limited to 2x8 instead of the having 2 full 16x lanes) wanted to know what the real world disadvantage would be when using current gen cards in sli ( not even thinking about pcie 3.0) at 8x vs 16x
 
No difference yet. Possibly later with new GT300 hardware or the new ati 5xxx stuff. Kyle mentiones this in the conclusion of his 1156 review and Anand also mentions it. Should be fine for a while.
 
notsane said:
No difference yet. Possibly later with new GT300 hardware or the new ati 5xxx stuff. Kyle mentiones this in the conclusion of his 1156 review and Anand also mentions it. Should be fine for a while.
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Agreed.
 
According to this Anandtech article on the i5 launch, there is a considerable disadvantage for GTX 275 SLI on a P55 board, at least in Far Cry 2: http://anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=9

Take that with a grain of salt because the article doesn't focus on gaming, but if one game has such a disadvantage with 8x/8x SLI it's likely that others will as well. OTOH it's possible that the results can be chalked up to how CPU limited Far Cry 2 is. Hmm... I don't know what to think. I guess someone really needs to do an in-depth article on this...
 
I can tell you that on my setup, in every game tested, there appears to be no performance hit....and I'm on PCI-E x 16, and PCI-E x 4 !!!!!
 
notsane said:
No difference yet. Possibly later with new GT300 hardware or the new ati 5xxx stuff.
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Haven't people been saying "maybe the next generation cards will utilize it"... ever since the introduction of PCIE2.0? Been a while, I'll say we'll be waiting and by the time it utilizes, PCIE3.0 will be standard.
 
in my sig,...will post a pic a bit later.
my old GTX295 with setup got around P21,000
 
PlatinumPC said:
I can tell you that on my setup, in every game tested, there appears to be no performance hit....and I'm on PCI-E x 16, and PCI-E x 4 !!!!!
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I'm curious as to how you assessed that there is no performance hit. While x8/x8 in benchmarks showed little difference in most cases vs x16/x16, it's a completely different story with x16/x4.

If you're running x16/x4, it has been proven that there is a severe bottleneck with the x4. In fact, in some cases, a single card will perform better than two cards in x16/x4 config. This is the whole reason I dropped my P965 mobo for an x48 (back when I was still on lga 775 chips) when I decided to go crossfire.
 
well all I can say is that your definately mistaken in this case. Single card is around 15-16k on vantage...and this setup destroys my old GTX295 scores in vantage, crysis, warhead etc etc.

As a matter of fact I started this topic when I saw first hand just how much BS there is out there about bandwidth saturation.
http://www.hardforum.com/showthread.php?t=1448847
 
PlatinumPC said:
well all I can say is that your definately mistaken in this case. Single card is around 15-16k on vantage...and this setup destroys my old GTX295 scores in vantage, crysis, warhead etc etc.

As a matter of fact I started this topic when I saw first hand just how much BS there is out there about bandwidth saturation.
http://www.hardforum.com/showthread.php?t=1448847
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You cannot make such a claim when running SLI GTX275 at only 1680 res !!
 
So he's probably right............there is no bottlenecking, at low resolutions. Why would you do SLI/Crossfire and not get a higher resolution monitor?
 
from the previews it def seems that 1156 is going to choke next gen multi gpu setups
 
lowteckh said:
Haven't people been saying "maybe the next generation cards will utilize it"... ever since the introduction of PCIE2.0? Been a while, I'll say we'll be waiting and by the time it utilizes, PCIE3.0 will be standard.
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Yes, but it sounds a bit too close for my comfort this time. If you aren't SLI'ing the two fastest cards out there and upgrading every few months when new cards come out then why worry. Like I said I reserve judgement until I see for from Kyle, but I wouldn't invest in this platform for high end SLI (with ongoing graphics upgrades) until I see the numbers. I'd rather just spend a few hundered more on the x58 platform and not worry, but I am not exactly sane.
 
this is the last thing keeping me from going micro with a P45 the board i can get is 8x all the time reguardless if theres another card in the other pci-e slot. if the 58** series doesnt saturate the 8x lanes then ill get matx board and case but if it shows its saturated then ill simply have to wait until i can afford a x58 setup.
 
RubbingAlcoholic said:
According to this Anandtech article on the i5 launch, there is a considerable disadvantage for GTX 275 SLI on a P55 board, at least in Far Cry 2: http://anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=9

Take that with a grain of salt because the article doesn't focus on gaming, but if one game has such a disadvantage with 8x/8x SLI it's likely that others will as well. OTOH it's possible that the results can be chalked up to how CPU limited Far Cry 2 is. Hmm... I don't know what to think. I guess someone really needs to do an in-depth article on this...
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What's strange though is that Crysis saw relatively no performance degradation between the two, at least with the two GTX275's, while Far Cry 2 is what saw large delta in performance.

Yeah, it would definitely be nice to see a separate, in-depth article looking at the potential performance loss for SLI/Crossfire on Lynnfield/P55, and at what point it's likely to begin occurring.
 
I read a review using p55 and x58 sli and crossfire. No difference when using 4870s or gtx 260s.
 
lowteckh said:
^^^ Isn't it also true that cards can't even use the full bandwidth of PCIE1.0 x16?
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PCI-Express 1.0/1.0a x16 slots have the exact same amount of bandwidth that PCI-Express 2.0 x8 slots have. I've heard arguments about latency differences but I've never seen anything solid on that. In any case, the answer is no. Cards today aren't saturating PCI-Express 1.0/1.0a x16 slots. It we see a card that can saturate PCI-Express 2.0 x8 slots it will most likely be a dual GPU card first before anything else. A theoretical 5870x2 or something like that might push it a bit but we'll have to wait and see.
 
Dan_D said:
This has been said for several generations now and it has yet to actually happen.
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in anandtech's article there was already a tiny, but noticable difference with 2 275s.
with 2 4870x2's there was a significant bottleneck, so its happened.
 
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