SLI Is Dead

[vegaguy5555]

As of now, SLI is dead in AC and rF2 in my rig.
I'm running 2 Strix 1080Ti's and show a 50% boost in the graphics test's I tried. But cuts FPS in half in AC and rF2, which I thought would be two sims that had the best chance. And that's after pawing through every thread I could get my hands on over the weekend. I just noticed I haden't run across one thread that stated straight out that SLI doesn't work anymore, so here it is.
And please!!
Some smart guys out there prove me wrong? My computer skills are not the best!! Lol!

 

[Jens Roos]

Both titles scales rather good in SLI, use nvidia profile inspector

I'm using almost std profile for AC:

rF2

other same as above


Use suitble tool and confirm PCIe 3.0 on both cars and high-bandwidth is detected

 

[vegaguy5555]

Both titles scales rather good in SLI, use nvidia profile inspector

I'm using almost std profile for AC:
View attachment 406053
View attachment 406054
View attachment 406055
View attachment 406056

rF2
View attachment 406057
View attachment 406058
other same as above


Use suitble tool and confirm PCIe 3.0 on both cars and high-bandwidth is detected

View attachment 406060

Thanks Jens!!
Oh that is great news!!
At work and can't wait to get home now!!

I only had one SLI wire harness ribbon bridging the cards. Would two be better or could this be part of my problem?
(But it did test 50% improvement)

Also, is VGA info in BIOS?

 

[vegaguy5555]

 

[vegaguy5555]

My Bus interface isn't matched.
How do I fix this?
Z97
4790K
16 ram

 

[Jens Roos]

Check your motherboard/bios documentation, it should be stated which slots to be used for multi-gpu, also, from my MB document, check that your mb bios is up to date.

dual ribbon will not fix the bus interface, that could detect as an hb bridge as it seems to differ, but testing is free and of no harm. hb bridge over single ribbon will normally show improvements at higher resolution, 1080p triples might be ok, not sure. If your system detect the 2 ribbons as hb bridge, then that should be ok.


when testing in-game, use suitable monitor that shows each card usage like this:

 

[vegaguy5555]

Check your motherboard/bios documentation, it should be stated which slots to be used for multi-gpu, also, from my MB document, check that your mb bios is up to date.

View attachment 406214
View attachment 406216

dual ribbon will not fix the bus interface, that could detect as an hb bridge as it seems to differ, but testing is free and of no harm. hb bridge over single ribbon will normally show improvements at higher resolution, 1080p triples might be ok, not sure. If your system detect the 2 ribbons as hb bridge, then that should be ok.


when testing in-game, use suitable monitor that shows each card usage like this:
View attachment 406219

Thanks again Jens!!
But I think it's my old 16 lane 4790k and 8 lane Z97 motherboard that is the bottleneck?
May have to look into an upgrade? A CPU and motherboard would be cheaper the a 30 series card that I don't think we can get ahold of this year anyway?
Will look for something that will would work with my DDR3 ram maybe?

 

[vegaguy5555]

What do you have for a cpu Jens?

 

[Jens Roos]

I'm on i7-7700K, i'ts about 3 years old now. Unless you know someone with an "left-over" motherboard my guess the possibility for an cost effective upgrade is low.

Had before that i7-4xxx with 1070 SLI, with little gain there I got the i7-7k instead, and after a while a changed to 1080 SLI instead.

One other "problem" with 1080TI and SLI is heat travel, there for I changed my MB again to my current one with 4 module width, and rebuild them to water cooled. So if you get GPU load at +2x90%, heat could be next issue if you have that load over longer time.

 

[vegaguy5555]

Are you using a PCX I think it's called? If I remember correctly?

 

[Jens Roos]

Not sure what PCX is referring to?

 

[Lizard Of Bodom]

Was

As of now, SLI is dead in AC and rF2 in my rig.
I'm running 2 Strix 1080Ti's and show a 50% boost in the graphics test's I tried. But cuts FPS in half in AC and rF2, which I thought would be two sims that had the best chance. And that's after pawing through every thread I could get my hands on over the weekend. I just noticed I haden't run across one thread that stated straight out that SLI doesn't work anymore, so here it is.
And please!!
Some smart guys out there prove me wrong? My computer skills are not the best!! Lol!

was it working OK before? something changed?
im still getting 2x performance with both cards running 90-99% efficiency. Scaling on AC is brilliant.
You sure its not shader patch issue? (sparks or grassfx kills SLI).

 

[Jens Roos]

For me CSP kills performance in SLI, hotlap can work if using light version from the IER car. Main thread goes high and fps drop, for race conditions vanilla AC only.

 

[Lizard Of Bodom]

For me CSP kills performance in SLI, hotlap can work if using light version from the IER car. Main thread goes high and fps drop, for race conditions vanilla AC only.

Odd, maybe your settings are too high? on my 3xFHD I can achieve 75fps with 20+ cars no problem, and its only 980SLI. I did fiddle with settings (less shadows, disabled sparks etc etc) but its easily achievable even on behemot tracks like LAC.

 

[Jens Roos]

Might be an combination of things, running 7680x1440p, and with vanilla AC race condition 100fps is ok, internal "benchmark" ~200fps. Using CSP fps drops to 60-70 fps and stutters in different ways.

Have not tried for a while now, so it might have changed.

 

[vegaguy5555]

I had a chance to sell one card so I did last night.
I'm thinking it's a motherboard issue.
It has killed 4 m2's, ram and this funny threading thing in AC.
And now this throttling the cards back to x8 2.0 from x16 3.0.

 

[Lizard Of Bodom]

I had a chance to sell one card so I did last night.
I'm thinking it's a motherboard issue.
It has killed 4 m2's, ram and this funny threading thing in AC.
And now this throttling the cards back to x8 2.0 from x16 3.0.

What chipset do you have? on some its perfectly normal to go from x16 to x8SLI if both slots are taken. It however doesnt affect performance much, you may loose 1 or 3 FPS but really it doesnt matter much. Recent tests on 3080 show that even on x8 you are still pretty ok and loose only few% of bandwidth.

On sidenote - yesterday's launch of 3080 and its performance makes a good contender to replace my 980SLI setup, seem like in few months would be doable and worth it.

 

[vegaguy5555]

What chipset do you have? on some its perfectly normal to go from x16 to x8SLI if both slots are taken. It however doesnt affect performance much, you may loose 1 or 3 FPS but really it doesnt matter much. Recent tests on 3080 show that even on x8 you are still pretty ok and loose only few% of bandwidth.

On sidenote - yesterday's launch of 3080 and its performance makes a good contender to replace my 980SLI setup, seem like in few months would be doable and worth it.

Z97A with the i7 4790k and 16 gigs of ram.
And have read that a few times. Little frame lose between x16 3.0 and x8 2.0 but in my case it cut fps in half and it wouldn't load at all in SLI at the end.
I even tried switching the cards around. I did have three SLI slots in the Z97A motherboard but couldn't get to the bottom one because the Strix Ti's were physically too big.
Oh well! It cost me 50 bucks but I did learn a little about SLI! Lol! And now I'm not wondering if I should have tried SLI!

 

[Neilski]

Recent tests on 3080 show that even on x8 you are still pretty ok and loose only few% of bandwidth.

But I think you're talking about x16 3.0 vs x8 3.0, whereas @vegaguy5555 was talking about x16 3.0 vs x8 2.0.
The (3080) tests I just looked at said that the former is indeed a few % hit on fps, while the latter is more than 10% - still not enormous but would be a bit painful given that you'd be forking out a lot of cash for a bleeding-edge card.