Nvidia SLI HB bridges

andicole0 · 31 May 2016 at 13:06

Biomorphs said:
It's 'recommended' but later on tonight I'll find out the best I can

Is this just applicable to 1080?
Andi.

Biomorphs · 31 May 2016 at 13:12

Yes apparently just the 1080 (so far) has been made to use both SLi connectors on the card for 'optimum' performance, mainly for 4K resolutions

HazardO · 31 May 2016 at 14:33

MooMoo444 said:
OcUK didn't think anyone would be daft enough to buy two 1080s? I jest.

Maybe not, but I suspect 1070 SLI will be popular for the 1440p high frame rate brigade.

seabiscuit said:
From what I've been told, we're waiting on availability from manufacturers guys. We hope to stock them as soon as we are able to, but I don't have any idea on pricing or an ETA.

Good to hear, but looking at the prices of the current gen2 bridges, they'll add at least £30-40 onto the cost of an SLI pair setup (Not that that's under OcUKs control).

If one of the GPU manufacturers was to offer a free SLI bridge to anyone who registered a pair of their 1070s or 1080s, they might find themselves a lot of customers.

Edit:

Biomorphs said:
Yes apparently just the 1080 (so far) has been made to use both SLi connectors on the card for 'optimum' performance, mainly for 4K resolutions

Oh I wasn't aware of that, but even with just one connector, the old flexible ones don't support the higher bandwidth, so it's looking like it will at least at one of the rigid aftermarket ones for best performance.

Mauller · 31 May 2016 at 15:08

You can use two standard bridges in place of the single HB bridge, it does the same job.

bishi · 31 May 2016 at 15:11

Mauller said:
You can use two standard bridges in place of the single HB bridge, it does the same job.

Do you have a source for this?

Klunt Bumskrint · 31 May 2016 at 15:14

Mauller said:
You can use two standard bridges in place of the single HB bridge, it does the same job.

That would mean that the EVGA bridge I have would be fine then.

HazardO · 31 May 2016 at 15:19

Mauller said:
You can use two standard bridges in place of the single HB bridge, it does the same job.

It's not just connecting both SLI connectors, the traditional flexible bridges do not support the data rate per cable that the newer rigid ones do.

There was a chart nvidia showed which suggested that there was support for 3 different data rates, the lowest was the only one possible on flexible bridges, the medium rate was supported by the previous generation of rigid "LED" bridges, and the new ones supported an even higher data rate.

Edit: This one..

nvidia-geforce-gtx-1080-recommended-sli-bridge-configuration-640px.png

Mind you I'm looking at SLI 1070s at 1440p 144Hz, so it looks like the mid range ones will be fine.

bishi · 31 May 2016 at 16:15

HazardO said:
It's not just connecting both SLI connectors, the traditional flexible bridges do not support the data rate per cable that the newer rigid ones do.

There was a chart nvidia showed which suggested that there was support for 3 different data rates, the lowest was the only one possible on flexible bridges, the medium rate was supported by the previous generation of rigid "LED" bridges, and the new ones supported an even higher data rate.

Edit: This one..

Mind you I'm looking at SLI 1070s at 1440p 144Hz, so it looks like the mid range ones will be fine.

You mean the chart in my OP?

HazardO · 31 May 2016 at 16:16

bishi said:
You mean the chart in my OP?

Yes, that one.

Armageus · 31 May 2016 at 16:30

Possibly a bit more info on it:

Guru3d said:
Beginning with NVIDIA Pascal GPUs, the two interfaces are now linked together to improve bandwidth between GPUs. This new dual-link SLI mode allows both SLI interfaces to be used in tandem to feed one Hi-res display or multiple displays for NVIDIA Surround. Dual-link SLI mode is supported with a new SLI Bridge called SLI HB. The bridge facilitates high-speed data transfer between GPUs, connecting both SLI interfaces, and is the best way to achieve full SLI clock speeds with GeForce GTX 1080 GPUs running in SLI. The GeForce GTX 1080 is also compatible with legacy SLI bridges; however, the GPU will be limited to the maximum speed of the bridge being used. Using this new SLI HB Bridge, GeForce GTX 1080’s new SLI interface runs at 650 MHz, compared to 400 MHz in previous GeForce GPUs using legacy SLI bridges. Where possible though, older SLI Bridges will also get a speed boost when used with Pascal. Specifically, custom bridges that include LED lighting will now operate at up to 650 MHz when used with GTX 1080, taking advantage of Pascal’s higher speed IO.

http://www.guru3d.com/articles_pages/nvidia_geforce_gtx_1080_review,4.html

BubbySoup · 31 May 2016 at 16:57

Is there any particular reason/advantage as to why nVidia have stuck with bridges?

HazardO · 31 May 2016 at 17:10

BubbySoup said:
Is there any particular reason/advantage as to why nVidia have stuck with bridges?

Yes, if you are using 8 lanes of PCIe gen3 per card or 16 lanes of PCIe gen2 per card, then the PCIe bus is already heavily loaded.

With SLI the cards need to share quite a lot of data and communicate with each other, in the above cases*, the spare bandwidth isn't available, so they basically implemented another one between the cards.

*Worst case scenario would be 3way SLI on a gen 2 system giving x8,x4,x4, where bandwidth is already oversubscribed, but that's probably one of the reasons they are trying to ditch 3 way SLI.

Klunt Bumskrint · 31 May 2016 at 18:03

HazardO said:
It's not just connecting both SLI connectors, the traditional flexible bridges do not support the data rate per cable that the newer rigid ones do.

There was a chart nvidia showed which suggested that there was support for 3 different data rates, the lowest was the only one possible on flexible bridges, the medium rate was supported by the previous generation of rigid "LED" bridges, and the new ones supported an even higher data rate.

Edit: This one..

Mind you I'm looking at SLI 1070s at 1440p 144Hz, so it looks like the mid range ones will be fine.

So unless I go 5K or surround then my EVGA one will be fine?

HazardO · 31 May 2016 at 18:37

Klunt Bumskrint said:
So unless I go 5K or surround then my EVGA one will be fine?

Without knowing whether your thinking of SLI 1070s or 1080s and whether that bridge has four or two connectors on it's difficult to tell, however..

Armageus said:
Possibly a bit more info on it:

http://www.guru3d.com/articles_pages/nvidia_geforce_gtx_1080_review,4.html

Armageus's link to guru3d suggests that it would be enough for 1080 SLI if it's the 4 connector version.

Klunt Bumskrint · 31 May 2016 at 19:02

HazardO said:
Without knowing whether your thinking of SLI 1070s or 1080s and whether that bridge has four or two connectors on it's difficult to tell, however..

Armageus's link to guru3d suggests that it would be enough for 1080 SLI if it's the 4 connector version.

It's the standard 3 way bridge, I'm only curious for the future. I'm sticking with Titan X goodness for now

Biomorphs · 31 May 2016 at 20:52

Just spent a while testing Unigine Valley:
I upped the settings as much as i could to test the cards:
Mode: 2560x1440 8xAA
Gsync off
6700K @ 4.5 Ghz

And i can safely say there is no difference in cables using this benchmark at least

I did notice that with one Ribbon cable attached - it suggested i use a faster/better quality cable

With 2 x Ribbon cables attached it didn't give me any such warning.

I scored around 5010-5080 using the same settings, the EVGA link.

Interestingly the program listed my card as:
GPU model:
NVIDIA GeForce GTX 1080 10.18.13.6825 (4095MB) x2

so not whats going on with the RAM it is picking up there, maybe just a program issue though?

If anyone else has an idea for a good SLi benchmark, ill be happy to try tomorrow.

Kaapstad · 31 May 2016 at 23:20

Klunt Bumskrint said:
So unless I go 5K or surround then my EVGA one will be fine?

Ran 4 way TXs @8k with an EVGA bridge and it runs ok with no loss of performance.

I wonder how much money NVidia will make on these new bridges.

caff · 31 May 2016 at 23:49

Biomorphs said:
Just spent a while testing Unigine Valley:
I upped the settings as much as i could to test the cards:
Mode: 2560x1440 8xAA
Gsync off
6700K @ 4.5 Ghz

And i can safely say there is no difference in cables using this benchmark at least

I did notice that with one Ribbon cable attached - it suggested i use a faster/better quality cable

With 2 x Ribbon cables attached it didn't give me any such warning.

I scored around 5010-5080 using the same settings, the EVGA link.

Interestingly the program listed my card as:
GPU model:
NVIDIA GeForce GTX 1080 10.18.13.6825 (4095MB) x2

so not whats going on with the RAM it is picking up there, maybe just a program issue though?

If anyone else has an idea for a good SLi benchmark, ill be happy to try tomorrow.

Thanks for the info. It might suggest that as Nvidia have stated, the HB SLI links are more suited to much higher resolutions of 4K+. So you compared the LED link to the ribbon one, essentially?

Vega · 1 Jun 2016 at 05:09

This video explains it all pretty well:

Klunt Bumskrint · 1 Jun 2016 at 06:32

Kaapstad said:
Ran 4 way TXs @8k with an EVGA bridge and it runs ok with no loss of performance.

I wonder how much money NVidia will make on these new bridges.

BUT how could you know.... Until you've tried the ~~snake oil~~ I mean the HB bridges, you may get more performance with one of those