SLI how to get the best performance

Scrap that, sorted but i cant find some of the bits people are suggesting?

0x000040F5 gives me 95% + on both cards with GTX 670 SLI but i have lots of flickering.

 

Gents here's an interesting one.

Computer 1 (mine):
Intel i5-3570k, Corsair Vengeance 2x8GB, ASUS p8z77-V Deluxe,
2x GXT670 SLI (Gigabyte)

Computer 2 (my friend's):
I5-750, 4GB RAM, Gigabyte GA-P55a mobo,
GTX780 (Asus, some factory o/c)

Computer 3 (another friend's):
Intel i5-3570k, Corsair Vengence 4x4 GB, Z77 Extreme 4 MoBo
GTX 670 (Gigabyte, single)

We're all running triple monitors, altho my friends are using 16:9 ones, while I'm on 16:10
so their resolution is 5760x1080 while mine is a tad higher at 5760x1200

using the same settings, same track, we run tests;
comp1: ~65fps
comp2: ~100fps
comp3 ~55fps


I've tried all sorts of things, but it seems in the end I'm not getting true SLI performance. (e.g. tried to run in windowed mode instead of full-screen, tried to tweak settings in the nvidia panel, etc)
I've looked at the cards' usage via MSI Afterburner, and both seems to be used heavily during rendering. So something is happening. Yet the performance remains.

Would you gents have any idea what's going on? Is it an SLI optimisation issue? Something else?

Thanks

 

Gents my post was merged here, but I don't think it is the same issue. My cards seem to be utilised nearly fully, yet the performance is lower than what I'd expect.
Btw....what is this talking about bits here? What bits, where and why? Sorry I'm completely in the dark with this.

 

Hi Guys,

Can someone please kindly post a screenshot of Nvidia Inspector settings. I have 2 x GTX 690 running on surround and trying to get SLI to work. Never used inspector before so some screen shots of settings will be great.

Thanks

 

I've been trying SLI with an old 9800GX2. Maybe it's the card (dx10) but I found my frame rates drop massively and start to vary wildly if I have the reflections per frame setting at anything other than 0. With it at 0 I get 38fps in single-gpu mode and 67 in AFR1 mode. At 1 it drops to about 50 and the frame rates start jumping around wildly. At 3 or higher I get lower frame rates than single-gpu mode.

I didn't use inspector to turn it on. I just did it in the nvidia control panel. Manage 3d settings, Program settings, Add custom profile for acs.exe. Seems some people don't have an sli option on that screen though.

 

Dear devs,

SLI with triple screens is not working at this stage, in this program.
When will you fix SLI handling, please?

After digging up all the scattered info in this thread, figuring out how/what to change to get "better performance", it turns out it does not work. Well, it does and doesn't - I get the performance, but it flickers madly, essentially unplayable. There's definitely something wrong, I should be getting about double the performance, it seems, but I can't.

Dear devs. I'm not expecting an instant fix (altho it'd be nice) however an acknowledgement of the problem and that it's on the list of bugs/updates would be nice.

Thank you.

ps I've tried these codes I've found around, neither working properly (or at all with the last one):
0x000040F5
0x080210F5
0x000110FB
0x080202F5

 

(Posted in another thread as well)
IT WORKS! OMG! Normally nothing works for me, nothing, I normally spend money and get no where when it comes to PC's parts, haha, but I through in another GTX-780 and then setup my NvidiaInspector as per link below and my frames (with all settings maxed!) went from 58 to 124!! WHAT THE! Just wrapped at the moment, game looks great, as do others! I am not sure what I did special, basically latest drivers and changes the SLI Comp. bits via iNvidiaInspector and away it went. Please, if I can help anyone, let me know and I will answer any questions you have to try and help if SLI is not working for you

https://forums.geforce.com/default/topic/540947/assetto-corsa-sli-profile/

PS. Boy I need AIRCON in the room now!! Haha heat is crazy!

 

If you have flickering, increase the reflection 'faces per frame' to a min. of 4, this cured it for me.

 

OH, finally is working for me too, better than using a sinlge VGA, hope to see some update to help more us with SLI/CROSSFIRE configuration! GG Kunos

 

Project cars is useless with X-Fire, AC seems to make good use of it, it's about time nVidia and ATI banged their heads together!!

 

I have the same problem now... Even with modifying to 000040F5 with inspector, my second GPU is not being used at all

 

Nvidia official SLI profile added in latest drivers :
https://www.assettocorsa.net/forum/i...e-addes-for-all-nvidia-owner.4905/#post-53937

 

Hi there,

I have been trying to make 660 sli working all this weekend. Whatever the drivers or the bits dx11 compatibility with inspector, I never get fluid animation.
I am using triple screen with a resolution of 3840x1024 and the VRAM is used around 1,4 Gb, so should be ok with 2Gb.

When I use only one 660, the performance is quiet good with no stutter as I get with two cards.

Is there anybody that succeed to make a similar setup working ?

Thanks

 

Haven't tried any nvidia inspector stuff in this thread, and am a bit scared to because finally after trying to days I've finally discovered that the way for me to get 120fps (rather than 20-40) on my twin 780's is by running at 5760x1080 with full screen unticked. No micro stutters. Nothing.

There is still cpu occupancy showing but it doesn't affect playability even with a good bunch if AI to race.

Thought it might be worth mentioning as I didn't think sli worked unless in full screen mode, but it does and uses 99% of both GPUs.

 

Thanks for the reply. In all my tests, I never tried with full screen unticked. I will check that tonight.
However I get also 97% usage on both cards without the compatibility bits stuff and performance is poor with fans at full speed!
You might try this inspector trick as I was able to reduce the usage of the cards around 50-60%, but with a lot of stutters as it seems that the vsync is not working properly.

 

Cool I'll give it a shot. Remember to edit your video.ini found in 'my documents' to your chosen res if you're going for triple screen.

Full screen is choppy as hell for me but windowed (which btw has no borders and looks exactly the same as full screen) runs perfectly. Hope it works for you mate.

 

I get around 95% usage on my cards in single car on track or if I turn up the GFX settings with lots of AI. AC is still fairly CPU bound with lots of AI its seems and so the GPU's are being a bottleneck at that point.

Here is solo car on track at fully maxed settings with build 0.8 I think it was. I dont use these settings in game though as I turn cube res to medium and 4 faces with no motion blur or combined aa.





Here is my regular settings in car solo



So pretty much any settings on my own I get high GPU loads with the regular NV SLI profile. Its only with other cars on track the loads drop as I suspect its a cpu limitation doing extra calculations holding back the GPU's, I have noticed a fairly big increase here with the latest NV Beta driver with GPU loads almost doubling with a full AI field compared to the previous WHQL driver and so the framerates in the same conditions have also both almost doubled.

Here is start of race back of grid regular settings as in sig 26 AI smoke very low, I get similar performance with smoke low but much bigger hit on medium high and ultra. See this thread on shadow settings IQ and performance hit for me. https://www.assettocorsa.net/forum/i...ses-massive-fps-drops.8317/page-2#post-114033



Here a full field 24 cars at Nurburgring from tv cam notice lower GPU loads.



See also this shadow and mirror bug I noticed effecting SLI.
https://www.assettocorsa.net/forum/index.php?threads/shadow-res-reduced-performance-drops.8028/

Some screens have HT on and some off, I found earlier builds HT off gave me better performance with lots of AI but now I have turned HT back on and its working better using more threads since 0.8.5

 

@Martyn : What have I to edit in the video.ini file?

@martcerv : thanks for this comprehensive post. How can I change HT ?

It seems that even if the last nvidia drivers have AC profile, sli is not yet working properly.

 

@rycil if you have a ht enabled processor the you can enable or disable HT within the bios. I was getting some pretty big slowdowns with HT off in the latest build but with it on with 18 cars at magione in a full race weekend with my reg settings I had a min 100fps but mostly staying at 145 maxing at 220 over the 2 15 min sessions and 10 lap race. HT off same conditions I would get similar max frame rate but min was stopping to 50 for no real apparent reasons. If your not getting the performance you hope for most things are worth trying once especially when there are possible SLI driver bugs where some things wont always have the effect you expect.

I think SLI is working as it definitely gives me a good boost over a single card but it can still get better and has some bugs that will hopefully be sorted. I am quite happy with the performance I get here and if it gets better then I will be happier. Comparing to RF2 where the default profile sli profile halve my fps and a workaround causes pretty major flickering issues with still not a great increase in performance AC is well ahead in SLI. It also looks and feels better to me so thats why I have stuck to AC mostly since getting it.