2 way SLI and 3 way SLI

[JimF_35]

I am sure it has been asked already but I am too lazy to read 9 pages of post to find it. Here it is, there is a rumor that you will only be able to do 2 way SLI on the new Pascal cards but there are other posts that this does not mean that you can not do 3 way SLI. So I am confused. I have watched some reviews and they say that there are 2 SLI fingers on the card but the 2 way SLI bridge uses both fingers so there is rumor that this is a duel channel SLI so does this mean that if you 3 way SLI that you will not get the advantages of the new "Enhanced" (or what ever they are calling it), SLI and is the new SLI really dual channel that uses both SLI channels?

 

[JimF_35]

Oops, meant for this to go under the GTX 1000 FAQ thread. If you want to move it, go ahead. Sorry.

 

[SliceT]

Yes, you can only use 2 cards for SLI with pascal, since they use both connectors to link each card.

 

[JimF_35]

BUT, does that mean you can ONLY do two way SLI or does it mean that if you do 3 way you will not be able to utilize the "enhanced dual channel" (or what ever they are calling it) SLI?

 

[rcald2000]

My understanding is the the GTX 1080 will only allow up to 2 way SLI. Beyond that, I have no idea. The SLI bridge will apparently allow twice the bandwidth of previous generations by the mechanism you've already stated. I wouldn't make any changes in your rig in anticipation until the cards release and actual performance reviewers get their hands on Pascal GPU's and release their findings. I would never believe anything that Nvidia or AMD says.

 

[JimF_35]

I was actually not planning on getting 3 way SLI because most games will not support 3 way SLI so it is a waste of money but I was having the discussion with friends at work and we were making guesses as to how it works. And there are those Synthetic Bench Markers who want to get the best speeds for bragging rights.

 

[ledhead11]

I read a post somewhere that more specifically stated that it may be possible to do either 3 or 4 way sli with the 10 series but Nvidia has stated they will not be supporting it this round(no drivers) and leaving to devs if they choose.

 

[redgarl]

3 way SLI or CF is a bad idea and result in lower FPS in half the games than 2 way SLI or CF. Not to mention scaling around 30-40%.

Also, a third card usually work in 8x4x4x which is a huge bottleneck. You need 8x to really enjoy a GPU potential.

 

[redgarl]

A special bridge could be avaialble, who knows, bu there is no limitation on that side.

 

[JimF_35]

3 way SLI or CF is a bad idea and result in lower FPS in half the games than 2 way SLI or CF. Not to mention scaling around 30-40%.

Also, a third card usually work in 8x4x4x which is a huge bottleneck. You need 8x to really enjoy a GPU potential.

Yep, said that and yes I am using a 5960x so no problems there (and who knows what the Broadwell-E will do but there is rumor that it will still work in the 2011v3 with bois update and if it based off of the current Brodwell then you may be right) but as I said above I personally am not going 3 way but there may be some Benchmarkers out there who just want the third card to simply get the best score possible regardless of the scaling.

 

[ledhead11]

3 way SLI or CF is a bad idea and result in lower FPS in half the games than 2 way SLI or CF. Not to mention scaling around 30-40%.

Also, a third card usually work in 8x4x4x which is a huge bottleneck. You need 8x to really enjoy a GPU potential.

I completely agree with you. Even if you have a CPU that supports 40 PCIe lanes you then need to do heavy research for a MOBO that will partition/populate it all evenly and fit all the cards. That combination can be tricky, plus power & cooling. It just becomes too much of a headache. I found that out while researching to what I have now. It was tricky but works(SLI 16x &16x, and a 8x PhysX-which I'll probably be dropping when I switch to a pair of 1080ti's since GPU PhysX is all but abandoned now).

 

[JimF_35]

3 way SLI or CF is a bad idea and result in lower FPS in half the games than 2 way SLI or CF. Not to mention scaling around 30-40%.

Also, a third card usually work in 8x4x4x which is a huge bottleneck. You need 8x to really enjoy a GPU potential.

I completely agree with you. Even if you have a CPU that supports 40 PCIe lanes you then need to do heavy research for a MOBO that will partition/populate it all evenly and fit all the cards. That combination can be tricky, plus power & cooling. It just becomes too much of a headache. I found that out while researching to what I have now. It was tricky but works(SLI 16x &16x, and a 8x PhysX-which I'll probably be dropping when I switch to a pair of 1080ti's since GPU PhysX is all but abandoned now).

You are probably right. Unless AMD does something with Cross Fire, there will be no incentive to produce a 16x by 16x by 16x boards. 🙁 No big loss as stated above, you would be hard pressed to find a game that would take advantage of 3 way SLI at 16x by 16x by 16x so the only reason to have it is for bench marking and bragging rights unless you are running a Folding server or something but then you would buy a multi CPU motherboard then.

 

[rcald2000]

+JimF_35 I believe that the lack of 16x 16x 16x configuration motherboards and lack of CPU lanes will first become a restriction for storage rather than for graphics. Intel Optane comes to mind. PCIe NVMe SSDs speeds are increasing at a greater factor than GPUs.

 

[ledhead11]

I've been saying for a while there's a lot of hype around the FE1080's and a bench test over at OC3d with 2 in the new SLI seems to show it. They used a pair of MSI GTX1080 Gaming in this rig(I didn't price it but I estimate around $3000-4000):

http://www.overclock3d.net/reviews/gpu_displays/msi_gtx1080_gaming_x_sli_review/1

2x MSI GTX 1080 Gaming X
Intel i7 6850K
ASUS X99 Strix
Corsair ROG Dominator Platinum 3200
Corsair RM1000i
Corsair LX 512GB OS
Corsair LS 480GB x2 Raid0 Games
Corsair H100i V2
Windows 10

A hex with 40 pcie lanes, 16x/16x for the cards. They really try to speak positively but really take a hard look at all the 4k tests. Some like Shadow of Mordor were 4k/120+FPS while Rise of Tomb Raider and the Metro's were down to 40-80 FPS in 4k. Now I know why they're called 1080, in 1080p or 2k they totally rock but are still struggling for demanding games in 4k.

 

[rcald2000]

+ledhead11 I'm a huge fan of tiny tom logan at OC3D. He happen to produce the very best review I've ever seen on two 295x2's in one rig. Below I've pasted both the video component of the GTX 1080 SLI review as well as the 295x2 in Crossfire.

OC3D: MSI GTX1080 SLI Review
https://www.youtube.com/watch?v=byqDvmxek5g

OC3D: OverKILL3D 295X2 Crossfire Review
https://www.youtube.com/watch?v=LPZe244Ufv0

 

[ledhead11]

+ledhead11 I'm a huge fan of tiny tom logan at OC3D. He happen to produce the very best review I've ever seen on two 295x2's in one rig. Below I've pasted both the video component of the GTX 1080 SLI review as well as the 295x2 in Crossfire.

OC3D: MSI GTX1080 SLI Review
https://www.youtube.com/watch?v=byqDvmxek5g

OC3D: OverKILL3D 295X2 Crossfire Review
https://www.youtube.com/watch?v=LPZe244Ufv0

Thanks for the links. He's unbelievably unbiased towards either side and I really appreciate that. I do like his reviews, he's very straight to the point but I'm still feeling a little underwhelmed when thinking about present and future 4k gaming on these first 1080 cards.

It was interesting to learn about the 3 different SLI bridges and how the fastest was still unavailable in the size/length he needed. The written review also mentioned the SLI driver/profile issues. I'm still a little dismayed that games like Doom(2016), GTAV, Witcher3 and many other games released in the last 6 months were not included as they've really become the newer 4k benchmarks.

The Metro 4k benchmarks are kind of funny when my system listed below easily rocks it at 4k/60fps(only compromise is AA 2x). That's because the Metro's were one of the few games listed that use a dedicated PhysX gpu driver plus SLI and I've got 2 970's in SLI and 780 for physx. Arkham City also performs similarily.

Some Vram monitoring specs would be nice as well. My laptop has 2x980m's(the clocks suck) but they each have 8gb vram. In 4k/60hz I've seen numerous games push from 4 to 6+gb and I don't believe it will be too long before the 8gb ceiling starts getting hit, but again that's why benches with newer titles would be nice.

When this thread was started I believe the question involved 3-way SLI which Nvidia has officially they won't support for gaming purpose. I believe the intent anyone would want to do that for gaming is 4k/120-144hz and its painfully obvious now that 2 can't do that(yet). I've been an Nvidia fan for over 10 years now and I know their updated drivers can make a difference. We'll just have to wait and see.

Thanks again for the links, I didn't know he did video reviews and it was fun to see that rig!!!