1080TI SLI not working in Skyrim

[L3s7ing]

"I'll have what she's having." ? ... sry couldn't hold back
Did you try switching the cards and replugging the monitor into the top card?
I think there was a way to reset the order... but simply reinstalling drivers doesn't seem to work. Hope I can find something onto that.
Sometimes gpu#2 is doing more work then #1 for me too (in my configuration) so I think it's ok that the lower card sometimes does more work in not fully balanced workloads.

Edited July 31, 2017 by L3s7ing

[Arkavick]

"I'll have what she's having." ? ... sry couldn't hold back

Did you try switching the cards and replugging the monitor into the top card?

I think there was a way to reset the order... but simply reinstalling drivers doesn't seem to work. Hope I can find something onto that.

Sometimes gpu#2 is doing more work then #1 for me too (in my configuration) so I think it's ok that the lower card sometimes does more work in not fully balanced workloads.

 

From the looks of things, what this guy says probably holds true for my board. I'm going to try and find the manual so I can validate this but its plausible that my motherboard just runs the bottom GPU as the primary card when In SLI.

 

It took some cheesing to get onto the bottom GPU but I did it. here

 

 

Unfortunately this still didn't fix the problem.

I figured I should try monitoring my CPU to see if there is any bottle neck. I'm no expert when it comes to these things so tell me what you think.

 

https://ibb.co/gOpzFQ

 

Now if this is a bottleneck, I have a 6core CPU with hyper-threading enabled. thread 0 and thread 2 seem to be doing most the work. This is just a theory and It may sound pretty dumb, but wouldn't disabling hyper threading essentially leave me with 6 twice as strong threads? This sounds like troll science to me but if the game needs more power per thread, recombining em seems like the most logical option.

Edited July 31, 2017 by Arkavick

[L3s7ing]

If I'm correct hyperthreading doesn't work exactly like that. It gives your OS the possibility to give on core multiple workloads, cause sometimes there are ways that one core could do two tasks at one time. Disabling HT would simply leave the core to work on the information given to him by one thread. Simply said each core has multiple modules which can do different things. Hyperthreading basically puts those modules into two threads and they can work independently without relying on each other. Somehow ... magic (pipelining ... but magic is easier).

However, those two "workloads" should be automatically managed to never interfere with each other, so disabling HT wouldn't do anything. It can be useful if you go on extreme oc cause of voltage handling and heat dissipation, but that should also be not very ground breaking.

==> Disabling Hyperthreading should not improve performance.

It's simply the engine that is limited to only use that many cores. So single core performance is more important, but your cpu is already very strong and on a high oc, which leaves not much room for improvements. Most good optimized games also only use 4 (or up to six) cores, which of course would be a great improvement.

 

Regarding the motherboard: I looked up the manual to see if I could fine something about that (cause I never heard anything about it and also use an Asus one), but couldn't find anything ... it also makes no sense to me, because your lower card runs on an 8x pcie lanes and the first on 16x ... so the first pcie slot should be the main card (like it's normally is).

Edited July 31, 2017 by L3s7ing

[Arkavick]

I took a look at the manual. Turns out all my PCIEs are X16 capable and because I run a 28 lane CPU this unlocks x16 and x8. I put the Master GPU under load with sli off and the bottom cards fans started spinning up. Checked out which card was under load in GPU Z and it was the bottom one running in X16???I checked the slave (top card not under load) and it says it's running in x8??? Weird right? I'm as confused as you are.

Apparently this motherboard has the capacity to run 3 way sli. I need to look more into this but It may just be a standard for 3 way SLI boards to make the middle slot master during SLI and configure the lane speeds accordingly. Even if the bottom card (middle slot) is the master and my monitors hooked into it, it says its running at x16 so there should be no performance loss right?

On a side-note, I don't know who's Idea it was to place the third PCIE slot by the superhugeass motherboard power jack but they should be fired. Only wafer fin water block GPU's could ever dream to fit in that slot.

Back to Skyrim: I disabled hyper-threading and i'm honestly surprised it did something. Apparently Skyrim is hard coded to run on two cores. It seems like Skyrim was using threaded cores rather than physical cores so only 1 physical core (two threaded cores) instead of 2 physical cores (4 threaded cores). Some others mentioned having this issue here.

I retested and the earlier CPU usage of 25% was way off. I was looking at entire CPU usage and not the actual process usage.

As a result of disabling hyper-threading CPU usage has gone form roughly 17% to 33% and average FPS has improved by about a third. Not exactly the double performance boost I was hoping for, but on the other hand fps is far more stable now and CPU usage is at what it should be considering the game should be running on 2 out of my 6 cores.

Unfortunately running on one GPU vs SLI still does nothing. The fact the game is essentially using double the CPU power for only a third FPS improvement seems even more wrong than before imo, and the double GPU utilisation for 0% FPS increase still makes me feel like I'm getting scammed.

How bout this. You think undervolt/underclocking my GPUs would do anything? It seems really counter intuitive, but what if my GPUs are too powerful for the the game, moreover the CPU itself? They might be stealing precious CPU time from the skyrim host process thus resulting in a slowdown of the game engine and the apparent lack of any SLI improvement. Stupid but worth a shot right? xD

I could also try overclocking one GPU and see if that increases FPS when running off it.

Edited August 1, 2017 by Arkavick

[L3s7ing]

My knowledge is at an end ^^ maybe the gpu numbers are simply switched somehow, but it would be maybe worth a try to ask your manufacturer for help (sometimes their support really helps out ... even if you can't believe it :D)

 

Disabling Hyperthreading shouldn't have brought an improvement in the first place ... but maybe the way Skyrim is coded just messes everything up. I would probably have tried to set up the cpu cores through the ini, but that's mostly because I switch between many games and some need more power than Skyrim (so taking away power from the cpu, in general, wouldn't work). That's why your usage is up at 33% now ... disabling half the cpu (not exactly, cause hyperthreading doesn't really double the performance, but roughly) means higher usage. But somehow Skyrim seems to work better for you this way.

When I first assembled my pc I tried turning off HT to go for higher oc with lower temps but couldn't let it stay there, cause it really cut my performance away (but I didn't play Skyrim often back then).

 

And the game doesn't really use the double cpu power. Cutting hyperthreading away maybe gives you a slight boost, but technically you don't just put two parts of a cpu together again. Like you don't just cut them in half by enabling it.

 

According to the gpu-thing, taking power away from it shouldn't do help you and it shouldn't also help the cpu. Your cpu will be either way at its limit with those cards and they aren't even on oc yet (if I saw it right in your pictures). They simply give your cpu as much room as it can get to work. Which isn't much in Skyrim...

 

It seems like your SLI worked in the 3d mark benchmark and superposition 4k benchmark so your setup seems to work fine in benchmarks generally ... maybe the games you tested weren't simply optimized (not according to Skyrim here).

 

However, I was wrong some times already ... so trying a bit around shouldn't hurt ...

Edited August 1, 2017 by L3s7ing

[Arkavick]

My GPU seems to have come somewhat stock overclocked. Its already boosting up to 2Ghz so I think I'll avoid touching it for now.

 

So under-clocking had no effect. I don't know what I was thinking. Any chance you could send me your profile just so we can rule out any last possibilities before I decide to hang myself? I'm gonna re-install the game too while I'm at it.

Edited August 1, 2017 by Arkavick

[L3s7ing]

https://ufile.io/h6qz3 Elder Scrolls V: Skyrim

Hope that works

[Arkavick]

https://ufile.io/h6qz3 Elder Scrolls V: Skyrim

Hope that works

 

I was so close to giving in... But then stuff got weird.

So here's a little progress update for ya. First off, thank you so much for taking the time out of your day to help me with this. I can never thank you enough.

Secondly, my next few tests garnered some really weird results. FPS was taken form the Dragonsreach stairs just so ya know. Its a good FPS ravine so you can get a idea of what minimum FPS to expect in game. The further you are form 60FPS, the more headroom for modding I say. Oh, and I'm not sure If I mentioned it here but It seemed like I was experiencing allot of under performance even on 1 GPU alone at first.

Initial test:

SLI 50-60FPS (Very sporadic/freq drops to 30-40FPS, 17%CPU)

1GPU 50-60FPS (Very sporadic/freq drops to 30-40FPS, 17%CPU)

After disabling hyperthreading:

SLI 60-70FPS (Stable, 33%CPU)

1GPU 60-70FPS (Stable, 33%CPU)

Applying your profile settings and reinstalling the game (Latest test):

SLI 90-100FPS (Stable)

1GPU 100-110FPS (Pretty Stable)

Main Menu (This is where things stop making sense):

SLI: 420FPS

1GPU: 2000FPS

escMenu:

SLI: 450FPS

1GPU: 2500FPS

^These new numbers are just plain weird. 4-5 Times the FPS on one GPU? WHERE ARE THESE FRAMES COMING FROM!?? Scratch that. WHERE ARE MY SLI FRAMES GOING!

On a serious note, I have no idea whats going on here but while SLI is screwy, It seems as though single GPU FPS is within normal boundaries for the card and no longer under-performing. Semi win? At least FPS keeps going up right? ^-^

I'd say we've got a lead now. We know my SLI can function on my system (and quite well at that). SLI negative-scaling is nothing new and probably has a definitive cause. Only question left is what's causing it and how to fix it so frames go up instead of down.

I'll do my best to gather more data and mess around with SLI settings in the mean time. This may very well yield some promising results.

Edited August 2, 2017 by Arkavick

[L3s7ing]

I think the fps in menus aren't worth looking at. I'm having the same in around 3 or 4 games. Maybe cause they're just so easy to render, one gpu simply goes faster without being held back by another.

 

I run some benchmarks on the same spot as you and had basically the same problem now.

60-65 FPS always... (getting a bit jealous on your single core performance there :tongue:)

 

4k without SLI, 4k with SLI, 5k without SLI, 5k with SLI. Sadly the game wouldn't allow me to go up to 8k or even higher :sad: so I could look into it further by simply raising the resolution.

 

Both gpu's aren't even doing much, but there's a difference between 4k and 5k.

4k the load on both is around 20% each and in 5k it rises to ~24%, while the cpu is still doing it's normal thing. Running for me on Core 1 and 7 and with always the same load.

 

For me it seems that the current state is cpu limited and even if I pack more gpu demanding things onto it, there's no performance loss.

Basically what I think is, that you could load much more gpu demanding things onto your game without losing performance. For me I only get more fps when there's less stress on the cpu.

Test for this would be loading your game up with as much 4k textures as you can get, without stressing the cpu more (like with more/better shadows).

For some games SLI only gets you benefits when one gpu can't do the job anymore.

 

In my tests I couldn't see any negative scaling in Skyrim with SLI ... so no Idea where that's coming from.

 

Sadly I can't confirm any of this for sure at the moment and might not be able to do much in the next days, got some exams coming in.

 

Edit:

Just tried something: I lowered some cpu intensive settings (shadow quality, actor-fading) to see what would happen.

(still using the whiterun spot, but not every time on the millimeter perfect spot. Somehow dsr or some settings destroyed my game, making every new save corrupt ^^)

 

Single GPU

got up to 60-70% load while running 5k at ~90-100 fps.

 

SLI

both cards around 55% usage at 5k with 95-110fps at 5k.

 

So gpu usage went up and fps also. Sure it's not a future option, cause good shadows look nice and we want to also see characters further away then 10m, but it could give information on SLI performance under better load. At least I hope so, got a lot of stuff on my mind, so correct me if I'm taking wrong turns somewhere.

There are also some SLI optimised ENB's which would be worth a look.

Edited August 2, 2017 by L3s7ing

[L3s7ing]

Not sure how the actual situation now is, but maybe, according to this video (https://youtu.be/VTmIBr1dpfM), reinstalling your os might help.

Just tripped over this while browsing yt, just thought it was worth mentioning in case your problem still exists.

 

Edit: Or maybe not. SLI underperforming is a similarity, but it's a different way of underperforming.

But looking into bios reset might be worth a shot, can't hurt to try, if nothing else helps.

Edited August 3, 2017 by L3s7ing