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PCI-E Bifurcation

Elerek

Cable-Tie Ninja
Jul 17, 2017
228
161
I have a question about bifurcation. I'm very new at this....

I'm in my way of building a new system for cad sketch up and Photoshop working, normally I render with vray, and I've been thinking about the best possible way to spend my money in order to have low render times.

After seeing that there's no difference at all in render time between Nvidia 2060 2070 and 2080 super.... And also that two 2060 super gives me better performance that a 2080 ti or even a Titan... I've come to the conclusion that the wiser thing is to buy a couple of 2060 supers with the bifurcation thing.

The question is: for those times that I play with my PC (not that often) will I be able to use that extra power or will I be playing as if I had a single 2060 super? Will I be force to use an sli bridge if I want them to work together while playing?

Thank you in advance.
Unless it's a DX12 game that the developers included multi gpu support for (which is basically no games) you need sli to use two cards. However

A) SLI is basically dead, not many games support it anymore and some games that don't support it will actually run worse.
B) The 2060 does not support SLI, only the 2070 super and up
C) If your work load doesn't scale from 2060 to 2070, why do you think it will scale by adding another 2060?
 

paulesko

Cable-Tie Ninja
Jul 31, 2019
198
118
Hello! Think you for your answer.

I didn't realised that 2060s don't support sli, what a fool I am. Anyway given your answer I realise it's not a very good idea to put two graphics cards to play with them because if software doesn't support it it's not going to be worth the money, I don't play that much, so it's not so important.

Regarding the C point, somehow vray doesn't scale from 2060 super to 2080 super (it didn´t improved from 2070 to 2080 before the "super" card were released so theres something there) but scales almost perfectly when adding more cards to the point that if the results with one 2080 ti is 100% the result with 4 2080 ti´s 408%
I know this by reading from Puget systems webpage from different articles in time, but I think its valid to have an idea.



In case you are interested, this is an older review where they say that 2070 is (odly) a tiny bit faster than 2080 rendering, and also two 2070 working together (looks like the original 2070 didn´t support sli either) is way faster than one 2080 ti and only slightly slower than two 2080 ti´s!!

I´m going away from the original matter of the post... my conclussion are that two 2060 super will probably work very well together with vray for render and its a better investment than lets say a 2080 ti, but for gaming I will probably have some problems, and in best of scenarios I can get a single 2060 super performance. I´ll think about it, but I guess I´ll go that way given my motherboard support bifurcation. And also I see it as an interesting thing to try.
 

TheArkratos

Caliper Novice
Mar 26, 2019
27
33
The question is: for those times that I play with my PC (not that often) will I be able to use that extra power or will I be playing as if I had a single 2060 super? Will I be force to use an sli bridge if I want them to work together while playing?
That's not really a bifurcation question. Full sized ATX motherboards and such use bifurcation internally to allow multiple GPUs, on an ITX board it just requires a riser.

As for GPU scaling in games, no idea what nvidia supports with their 20 series cards, last dual GPU system I had was AMD with RX480s and before that it was Nvidia GTX 970s. Look up benchmarks?
 

TristanDuboisOLG

Average Stuffer
May 10, 2018
75
15
I have a question about bifurcation. I'm very new at this....

After seeing that there's no difference at all in render time between Nvidia 2060 2070 and 2080 super.... And also that two 2060 super gives me better performance that a 2080 ti or even a Titan... I've come to the conclusion that the wiser thing is to buy a couple of 2060 supers with the bifurcation thing.

The question is: for those times that I play with my PC (not that often) will I be able to use that extra power or will I be playing as if I had a single 2060 super? Will I be force to use an sli bridge if I want them to work together while playing?
I modified the quote, but anyway, the 2060 doesn't have a space for an SLI bridge, (not called that now either), you can sometimes get a boost in performance from software sli programs like Different SLI Auto.

It's strange to me though that you didn't see an increase in performance with a better gpu... Perhaps the person's testing methodology was flawed or they were using CPU as the render device? I see here that there is quite a difference...

To my knowledge both your game and motherboard would need to support SLI for them to work together while playing.
 

paulesko

Cable-Tie Ninja
Jul 31, 2019
198
118
That's not really a bifurcation question. Full sized ATX motherboards and such use bifurcation internally to allow multiple GPUs, on an ITX board it just requires a riser.

As for GPU scaling in games, no idea what nvidia supports with their 20 series cards, last dual GPU system I had was AMD with RX480s and before that it was Nvidia GTX 970s. Look up benchmarks?
The only benchmarks I´ve been looking at are those of Vray for rendering, and on those it looks like nvlink is not usefull because it doesn´t give any bump in performance if you use it, so a pair of 2060 without the link makes sense, it´s just that I wont benefit from it for playing, but as I say it´s not that important.

I modified the quote, but anyway, the 2060 doesn't have a space for an SLI bridge, (not called that now either), you can sometimes get a boost in performance from software sli programs like Different SLI Auto.

It's strange to me though that you didn't see an increase in performance with a better gpu... Perhaps the person's testing methodology was flawed or they were using CPU as the render device? I see here that there is quite a difference...

To my knowledge both your game and motherboard would need to support SLI for them to work together while playing.
I´ll look into that software sli that you mention, it´s been some years since the last time I build a computer and some things have changed... I need to recycle haha, thank you for the info.

When I say I don´t see an increase performance it´s because it´s almost nothing, for example in the link you posted, the 2070 render un 68 seconds and the 2080 in 69 so the 2070 is actually better than the 2080, but the difference is so small that I call it a tie. Also, a 2070 sli (correct me, but it doesnt have nv link either, it´s not the super version) renders in 33 seconds a 2080 sli in 35 seconds and a 2080 ti sli in 26 ... to compare, a single 2080 ti renders (always same scene) in 52 seconds.

If you look at the "super" review the behaviour is the same (althoug the vray version is newer) so theres something there working strangely https://www.pugetsystems.com/labs/articles/V-Ray-Next-GPU-Roundup-NVIDIA-GeForce-RTX-SUPER-Performance-1548/

In this test if 2060 is 100% in performance:
2060 super 136%
2070 135%
2070 super 137%
2080 132%
2080 super 132%
2080 ti 178%

This is what I call a tie between the 2060 super and the 2080 super being the more expensive card the worse whic is indeed a very interesting and weird result. Here is a matter of buying a couple of 2080 or a 2080 ti

Anandtech gets similar results. https://www.anandtech.com/show/14586/geforce-rtx-2070-super-rtx-2060-super-review/13

Thank you for your help, for now I´m going to read a couple of long threads I´ve found abou bifurcation to learn if it´s realiable and then make a decision.
 
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tezcan

Case Bender
Sep 21, 2019
2
1
I'm thinking to try bifurcation on the Gigabyte X570 ITX board with SLI'ing a couple 2070 supers or 2080/super/TI's.

For my ideal config though there are several hurdles, can you guys please help/advise me on these?:

1. How to enable SLI support on the motherboard, will this guide work for my motherboard?: https://www.win-raid.com/t2717f16-GUIDE-How-to-make-your-Mainboard-SLI-compatible-without-a-BIOS-mod.html
2. I want two single slot water cooled GPUs side by side and there is no NVLINK for this. I am thinking I'll have to make (jerry rig) my own since it looks like they are using PCI-E connectors. I think it is a PCI-E 4x connector. Has anyone been able to get that working?
3. I've seen riser cards that support this dual single slot side by side config (a little costly but nothing compared to the GPUs) but probably have to solder some voltage rails to it. Or will it just work with my PCIE 6/8 pin power going into the cards? Any success with that here?
4. My PSU is 750 watts and planning on Ryzen 12 or 16 core CPU... enough juice? I think I might have to go with 2080 non-super and non-TI to stay in the power budget...
5. Cost, time, etc. on getting this to work, not sure if it worth my time or money. Also, yeah SLI is kind of a joke and not recommended pretty much ever, but it is more for an experiment, hobby and proof of concept for me. I actually barely ever gamed in the past 9 years but hope this will change with this rig. Should I even bother or just get a 2080 Ti and call it a day?
 
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The-Alchemist-404

Caliper Novice
May 14, 2019
26
8
so with a new concept in mind [no multigpu setup] i was looking for a riser card that has an x4 x4 x8 layout to bifurcate from the x16 slot found on the gigabyte x570 itx so far found this:


wich as far as i know is exactly what i need, the issue is that idont know if it will work or if its available as a stand alone card
the thing should work to hold a sata controller, a networking card and a graphics card

Edit: the card in the picture is the RSC-T2R-884 from Super Micro found here

Edit No. 2:
Holy smokes!!!, found the consumer version https://peine-braun.net/shop/index.php?route=product/category&path=65_61


i migth ask him for a shorter version of the same card to work on my case, i cant believe that forgot about c_payne
 
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The-Alchemist-404

Caliper Novice
May 14, 2019
26
8
"front and back parts can be sawn off at the white line if not needed "
but i mean how do i mount it to the case?, i was thinking on moving a couple of lines to acomodate for two mounting holes, but that sould work as a prototype
 

forvak

Caliper Novice
Oct 14, 2019
21
11
I'm debugging an issue with Bifurcation using the Asrock X570 Gaming ITX motherboard, Sliger SM560 riser, Zotac GTX 1070, and (eventually) a Mellanox ConnectX-4 Lx dual 25 Gigabit NIC. The GPU displays the BIOS in all slots and bifurcation settings, but Windows 10 doesn't use it in the second slot when x8x8 is enabled in the BIOS. If anyone has any advice/experience in debugging these issues I'd be grateful.

Full Thread:
 

TheArkratos

Caliper Novice
Mar 26, 2019
27
33
So there's no hope in getting my Asus X470I to work with bifurcation?
Asus seems to ignore that bifurcation exists for ITX. I've asked their reps in person and been given the run around and asked on Twitter where they blatantly ignore it.

im thinking on a custom case, working on the desing tho
If you are interested I'm working on a case, trying to support too much IO in an ITX setup.



My goal is to eventually pitch it so someone can manufacture my dream case. I've talked with Sliger briefly about it a few times.

Edit: Theoretically it would not be hard to turn the 8x8x bifurcation riser into a 8x4x4x riser, because I already have the spacing for it.

Double Edit: Yes I'm running a M.2 -> PCIe 4x adapter for my 10gb nic
 
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The-Alchemist-404

Caliper Novice
May 14, 2019
26
8
If you are interested I'm working on a case, trying to support too much IO in an ITX setup.
Nice concept, i was playing with the idea myself, but for the proyect im planing to use bifurcation is a dual itx system, a server side and a "normal user" side using a revolt power supply to power both
 
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