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loki1944
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- Oct 31, 2013
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Eggz :
FOLLOW UP QUESTION FOR TOM'S
RE: SLI Bridge Bandwidth - Will Tom's think of, execute, and publish results of tests showing whether the very low bandwidth of the SLI Bridge poses a bottleneck? I have a strong feeling it does. The connectors are one of the few pieces (if not the only piece) in high-performance systems that rely on technology more than a decade old, and perhaps it's nearly two decades old.
But look at how long Nvidia's been using this.
Manufacturer: NVIDIA
Type: Multi-GPU
Release date: 2004
Predecessor: Scan-Line Interleave
PCI-e first came out the same year (2004) with PCI-e 1.0, and the max bandwidth of a x 16 slot was only 4 GB/s. So the SLI Bridge provided up to a 25% increase. Okay. But now the PCI-e slots have quadruple the bandwidth, with roughly 16 GB/s for PCIe- 3.0 x 16.
The cable itself may actually be much older than 11 years. Today's SLI bridge may in fact use the same cable configuration that 3Dfx used (and 3Dfx started SLI) starting back in 1998.
If current SLI Bridges are just prettier versions of the original SLI cables, that would make the modern SLI bridge a 17 year old interface on cards like the Titan X! After researching without finding definitive information, it certainly does appear that the 3Dfx SLI cable and the Nvidia SLI Bridge could differ only by appearance.
Regardless of the age, however, the fact remains that modern SLI bridges are limited to a measly 1GB/s. That was originally to spare PCI bandwidth, but we've moved on to PCI-e, which is much faster. We have plenty of good information showing that PCI-e 3.0 provides excessive bandwidth for GPUs beyond x 8 (click image below for link).
If PCI-e 3.0 x 8 is enough for even the fastest cards, then x 16 (with twice the bandwidth) is WAY more than enough. So why, then, would it make sense to use an SLI Bridge when the PCI-e bus has potential to do a far better job?
Perhaps the Nvidia purchase agreement used to acquire 3Dfx has a condition that requires the connector technology to stick around. Maybe there's not enough of an SLI market for Nvidia to allocate R&D toward the issue. And maybe 1 GB/s is actually plenty of bandwidth given the current state of things. Who knows.
The only clear thing to me on this topic is that the SLI Bridge seems to clearly not fit. If possible, it should be updated. And if not possible for some reason, there should be information telling people when the issue preventing innovation will expire.
RE: SLI Bridge Bandwidth - Will Tom's think of, execute, and publish results of tests showing whether the very low bandwidth of the SLI Bridge poses a bottleneck? I have a strong feeling it does. The connectors are one of the few pieces (if not the only piece) in high-performance systems that rely on technology more than a decade old, and perhaps it's nearly two decades old.
But look at how long Nvidia's been using this.
Manufacturer: NVIDIA
Type: Multi-GPU
Release date: 2004
Predecessor: Scan-Line Interleave
PCI-e first came out the same year (2004) with PCI-e 1.0, and the max bandwidth of a x 16 slot was only 4 GB/s. So the SLI Bridge provided up to a 25% increase. Okay. But now the PCI-e slots have quadruple the bandwidth, with roughly 16 GB/s for PCIe- 3.0 x 16.
The cable itself may actually be much older than 11 years. Today's SLI bridge may in fact use the same cable configuration that 3Dfx used (and 3Dfx started SLI) starting back in 1998.
If current SLI Bridges are just prettier versions of the original SLI cables, that would make the modern SLI bridge a 17 year old interface on cards like the Titan X! After researching without finding definitive information, it certainly does appear that the 3Dfx SLI cable and the Nvidia SLI Bridge could differ only by appearance.
Regardless of the age, however, the fact remains that modern SLI bridges are limited to a measly 1GB/s. That was originally to spare PCI bandwidth, but we've moved on to PCI-e, which is much faster. We have plenty of good information showing that PCI-e 3.0 provides excessive bandwidth for GPUs beyond x 8 (click image below for link).
If PCI-e 3.0 x 8 is enough for even the fastest cards, then x 16 (with twice the bandwidth) is WAY more than enough. So why, then, would it make sense to use an SLI Bridge when the PCI-e bus has potential to do a far better job?
Perhaps the Nvidia purchase agreement used to acquire 3Dfx has a condition that requires the connector technology to stick around. Maybe there's not enough of an SLI market for Nvidia to allocate R&D toward the issue. And maybe 1 GB/s is actually plenty of bandwidth given the current state of things. Who knows.
The only clear thing to me on this topic is that the SLI Bridge seems to clearly not fit. If possible, it should be updated. And if not possible for some reason, there should be information telling people when the issue preventing innovation will expire.
But then they couldn't sell sli bridges.
endeavour37a
Honorable
- Feb 25, 2013
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About the 980Ti, source: http://videocardz.com/55419/nvidia-geforce-gtx-980-ti-confirmed-to-feature-6gb-memory
While everyone is waiting for Radeon 300 series, NVIDIA is busy developing yet another flagship card that will target yet unreleased Fiji-based Radeon graphics cards.
Some of you might have noticed that we didn’t cover recent GTX 980 Ti rumors. It was for two reasons: nothing was confirmed (not even the name of the card) and secondly almost everything that was posted was based on speculation. This post however, is based solely on our new information provided by credible source (thanks Jen-Hsun!).
To sum up:
cheaper GM200-based graphics card is codenamed GeForce GTX 980 Ti;
GeForce GTX 980 Ti has GM200-310 GPU (Titan X is GM200-400)
GeForce GTX 980 Ti has 6GB of GDDR5 memory;
GeForce GTX 980 Ti will be available with custom cooling solutions;
GeForce GTX 980 Ti has 5 display outputs: 3xDP, HDMI, DVI-I
NVIDIA GeForce GTX 980 Ti is expected to arrive in few weeks. Stay tuned for more.
- Oct 30, 2004
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We have three SLI systems:
Twin 780's w/ 26% OC (21% on memory) under water 144 Hz 1080p
Twin 560 Ti's overclocked 28% on air 120 Hz 1080p
Twin 970's not yet OC'd in air.... Acer Predator (144 Hz 1440p) arrived today so will OC this weekend.
No issues to date with **any** of the cards other than:
a) SLI profiles not ready for prime time during beta and sometimes not so hot in 1st weeks of release.
b) Battlefield 4 .... keeps improving with each patch but this game has been unique. My son's and other user were just turning it off and instead of crashing in 20 minutes, they might get an hour. Noiw they get as much as 2 hours.
That hardly represents "don't work half the time" and as for the "bugs", haven't experienced them. There are some games that don't work well butr certainly there's no AAA games among them. The ones that don't scale well or even the extremely rare - scaling are of no concern as these "off games" are at 100+ fps anyway.
Out of 17 games in Techpowerup's Test Suite (1440p) for the 970 in SLI:
0 has negative scaling
2 have scaling below 65%
5 games have > 90%
10 games have > 80%
I just don't know how that can be described as "not working half the time". If you are looking for > 60 fps on a 144 Hz monitor, one 970 can't cut it on 10 outta 17 games.... SLI manages all but 1. And, yes, using a non reference card easily brings that 58.7 in the reference Tomb Raider over 60 fps.
Tomb Raider goes from 29.8 to 58.7 an increase of 97%
Battlefield 3 goes from 62.1 to 121.4 an increase of 95%
Far Cry 3 goes from 35.6 to 68.8 an increase of 93%
Crysis 3 goes from 22.5 to 43.3 an increase of 92%
Thief goes from 70.8 to 136.1 an increase of 92%
Bioshock Infinite goes from 76.7 to 143.9 an increase of 88%
Splinter Cell: Blacklist goes from 49.5 to 92.2 an increase of 86%
Battlefield 4 goes from 45.0 to 83.2 an increase of 85%
Metro LL goes from 40.7 to 74.6 an increase of 83%
Batman: Arkham Origins goes from 81.8 to 148.3 an increase of 81%
Watch Dogs goes from 50.0 to 85.1 an increase of 70%
Crysis goes from 44.1 to 74.0 an increase of 68%
Grid 2 goes from 84.6 to 141.8 an increase of 68%
Assassins Creed goes from 37.5 to 61.8 an increase of 65%
WoW: Mists of Pandaria goes from 110.8 to 174.8 an increase of 58%
Diablo III: Reaper of Souls goes from 157.0 to 220.8 an increase of 41%
The average of all games is 75% .... dang, I'm more than satisfied. Makes 1440p a pleasant experience tho no pair of cards at this point is ready for 4K at 60 fps across the board .... I expect that by the time there's 144 Hz monitors at 4k compatible w/ new display port spec, we'll have cards that can do handle it.
Twin 780's w/ 26% OC (21% on memory) under water 144 Hz 1080p
Twin 560 Ti's overclocked 28% on air 120 Hz 1080p
Twin 970's not yet OC'd in air.... Acer Predator (144 Hz 1440p) arrived today so will OC this weekend.
No issues to date with **any** of the cards other than:
a) SLI profiles not ready for prime time during beta and sometimes not so hot in 1st weeks of release.
b) Battlefield 4 .... keeps improving with each patch but this game has been unique. My son's and other user were just turning it off and instead of crashing in 20 minutes, they might get an hour. Noiw they get as much as 2 hours.
That hardly represents "don't work half the time" and as for the "bugs", haven't experienced them. There are some games that don't work well butr certainly there's no AAA games among them. The ones that don't scale well or even the extremely rare - scaling are of no concern as these "off games" are at 100+ fps anyway.
Out of 17 games in Techpowerup's Test Suite (1440p) for the 970 in SLI:
0 has negative scaling
2 have scaling below 65%
5 games have > 90%
10 games have > 80%
I just don't know how that can be described as "not working half the time". If you are looking for > 60 fps on a 144 Hz monitor, one 970 can't cut it on 10 outta 17 games.... SLI manages all but 1. And, yes, using a non reference card easily brings that 58.7 in the reference Tomb Raider over 60 fps.
Tomb Raider goes from 29.8 to 58.7 an increase of 97%
Battlefield 3 goes from 62.1 to 121.4 an increase of 95%
Far Cry 3 goes from 35.6 to 68.8 an increase of 93%
Crysis 3 goes from 22.5 to 43.3 an increase of 92%
Thief goes from 70.8 to 136.1 an increase of 92%
Bioshock Infinite goes from 76.7 to 143.9 an increase of 88%
Splinter Cell: Blacklist goes from 49.5 to 92.2 an increase of 86%
Battlefield 4 goes from 45.0 to 83.2 an increase of 85%
Metro LL goes from 40.7 to 74.6 an increase of 83%
Batman: Arkham Origins goes from 81.8 to 148.3 an increase of 81%
Watch Dogs goes from 50.0 to 85.1 an increase of 70%
Crysis goes from 44.1 to 74.0 an increase of 68%
Grid 2 goes from 84.6 to 141.8 an increase of 68%
Assassins Creed goes from 37.5 to 61.8 an increase of 65%
WoW: Mists of Pandaria goes from 110.8 to 174.8 an increase of 58%
Diablo III: Reaper of Souls goes from 157.0 to 220.8 an increase of 41%
The average of all games is 75% .... dang, I'm more than satisfied. Makes 1440p a pleasant experience tho no pair of cards at this point is ready for 4K at 60 fps across the board .... I expect that by the time there's 144 Hz monitors at 4k compatible w/ new display port spec, we'll have cards that can do handle it.
- Oct 30, 2004
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I can't help but think there was a bit of predatory pricing going on with nVidia and the 970. My jaw dropped with the quarterly earnings report from AMD last month. Market share has dropped precipitously. Tho contrary to my personal interests, I'm hoping that prices for the 390x and 980 Ti remain more commensurate w/ previous generations. In the long run, it's not healthy for the market space to have such a wide disparity (3:1) as we have now
endeavour37a
Honorable
- Feb 25, 2013
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I could not agree more, I think they keep Intel honest as well as Nvidia. I hope they hit it out of the park with the 390/390x (Fiji) cards to gain a bigger share of the market (great graphics!). Without AMD we would perhaps be living in a much different world concerning CPU and GPU pricing. Thanks for the great info in both posts!
- Oct 30, 2004
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- 14
- 99,960
?
I have built dozens of SLI builds..... never bought a bridge. If there's a market for them, maybe I should sell all the one tucked away in MoBo boxes from old builds
soldier5637
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- May 7, 2013
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- Oct 30, 2004
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It's a "I'll believe it when i see it thing for me"
Freesync was gonna be great too and at least so far, it ain't
Freesync was gonna be great too and at least so far, it ain't
loki1944
Distinguished
- Oct 31, 2013
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JackNaylorPE :
?
I have built dozens of SLI builds..... never bought a bridge. If there's a market for them, maybe I should sell all the one tucked away in MoBo boxes from old builds
Not sure what you mean, I just know that without a SLI bridge SLI does not work. Crossfire however, does not need a bridge anymore.
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