crossfire setup

leaumat · Feb 27, 2021

Hello,
i have a question about my crossfire.
everything looks fine in solo
with afr friendly on amd drivers
and maxed out on 1080p in game,
i went from 60 fps to 120 fps i didn't expect to double it so that's great !

But when i try to race against ai, it totally messes up...

with single card i could race with 40cars max on medium graphics setup,
(between 45 and 55 fps at start and gradually up to 60fps after the first/second lap depending on the track) without feeling lags.

With crossfire i can barely have 24 cars on medium graphics setup pp filter disabled, more car or higher graphics setup and it is totally laggy..

I tried many different setups but nothing enough stable..

my config: i7 2600k oc at 4,4ghz
crossfire r9 290x
16 gb ddr3

custom shader patch and sol 1.5 installed

Is someone had this problem and solved it ?
Any suggestion would be welcome !

thanks
leau

RasmusP · Feb 27, 2021

For me this sounds like crossfire is having some cpu overhead.
In ac, being alone on track is super easy for the cpu but with 24 ai, most CPUs struggle to keep high fps!

With my 2600k @ 4.4 GHz and ddr3 2133 I dropped to 60 fps when racing against more than 20 cars. Ai or online didn't matter but AI does cause even more load on the cpu.

What you should do to get more knowledge about what's causing it for you:

Enable developer apps in the content manager - assetto - apps settings.

Then open the two performance apps. Not sure which is which but one is the "fps" performance app and the other is a monitor symbol..

Anyway, you need the one that shows the "main_t" as the first line.

That's the main cpu thread. When it goes close to 100, you get stuttering, fps drops and even jumping cars and other issues.

Even my new 10600k with 6 cores, 12 threads and 4.9 GHz on all cores goes to 93% during race starts. But I have my fps limited to 90 fps since I have a 100 hz gsync monitor and this keeps my cpu from hitting too high % in the main_t.

So what you have to do:
Check the main_t with only one graphics card and then with crossfire.

It might not be the issue but it's one thing to check first

leaumat · Feb 27, 2021

thanks for your reply RasmusP,

i just made several tests, looking at the main-t..

First i didn't notice any difference between crossfire desabled in amd drivers or with 1 card removed of the case.

i made tests always with same configuration tracks and cars at spa in solo, 24cars ai, 40cars ai with and without crossfire

i noticed that i am often at main-t 95% whether it be in solo or in race with 24 cars with maxed out and photographic pp filter

except with vsync ON what maintains cpu around 50% in solo so that's why i left it ON

for race 40 cars AI with lower graphics setup and crossfire desabled
i'm around 45 fps and main-t 95% at start and fluctuates during race between 50/60fps and main-t 80/95% which is pretty playable

with crossfire ON in race 40 cars AI and same graphics setup
fps fluctuates between 20-30fps and main-t goes to 120% sometimes higher

Lizard Of Bodom · Mar 1, 2021

I have SLI so it may be completely different but in my case "particles fx" and similar settings (sparks/fireworks etc) was causing totally odd FPS drops to the point where it cant be explained logically. Normally I have 75fps on 3k setup, but with those enabled it drops to 40fps or around, defo SLI incopatibility/bug/whatnot but with this option off its zero issues. I recomment experimenting with setup and disabling everything, and if it works ok - re-enabling options one by one until you pinpoint the problem.

Or maybe its not related at all, dunno, but worth a shot

leaumat · Mar 1, 2021

thanks Lizard, i will take a look at this !
i temporarily solved the issue, with higher graphics settings ( not maxed out but almost) back to 40 cars at 60 fps but only kunos cars... it seems that crossfire doesn't appreciate modded cars...

What is your sli and cpu by the way ?

Lizard Of Bodom · Mar 1, 2021

leaumat said:
thanks Lizard, i will take a look at this !
i temporarily solved the issue, with higher graphics settings ( not maxed out but almost) back to 40 cars at 60 fps but only kunos cars... it seems that crossfire doesn't appreciate modded cars...

What is your sli and cpu by the way ?

Ryzen 3700x and pair of GTX980. Old cards, yes, but works perfectly in SLI with AC and for tripleFHD, one was not coping with FPS.
Planned to upgrade this year to RTX3series but you know...

leaumat · Mar 2, 2021

Well, i tried to desable the particulesFX extension but i didn't see any improvement..+ i let the fireworks always on and it seems to have no impact on the framerate..
I just let new smoke desabled 'cause it was bugged but already did it before
I'm back on the modded cars, it should be the problem with some 4k/hd skins/templates