Cpu and GPU not fully used but framerate decrease

Yeah RAM speed / latency is one of the obvious ones.

A thing that stroke me when doing my tests, is that for some reasons you can't rely completely on the usage percentage, I didn't had so much GPU performance headroom showed in monitoring tools before CPU upgrade, it's not black or white and bottlenecks do exist before seing 100%.

The monitoring tools are reporting the use of our devices based on a typical use and I'm pretty sure some use case can report less than 100% but still be at maximum device capabilities for that specific use case.

 

Bad thing is, that I can't find out if an upgrade of memory with lower latency would really help. Going from DDR4 3200 CL17 to DDR4 4133 CL17 reduces latency from 10ns to appr. 8ns only.

 

such frequencies can be harder to reach as it also depends on your IMC quality (integrated memory controller on your CPU) but going from 10.63 ns to 8.23 ns is a massive improvement. I've convinced a couple of VR user to make the RAM upgrade to gain in the 20% true latency ball park, and the fps gain was in the 10%

Also on Intel I can't tell you how to get the right timings, on AMD it's pretty simple there is a perfect tool for that (1usmus Ryzen DRAM timing calculator), but pretty sure you could find something similar.

What matters is the true latency of the kit, manufacturers usually invoice a large premium on high frequency kits, and you need to remember 3600 is pretty easy to achieve on all platforms, higher is really down to silicon lottery. Of course when you know what timing to set, you can play with combinations of speed/timing that are resulting in more or less same true latency. TLDR it's pointless to buy an expensive 4500 MT kit, it is so unlikely you run it at that speed, and timing would be pretty loose.




If you want to look at users happy with the RAM upgrade look at these:
https://www.assettocorsa.net/forum/...ng-to-be-addressed.59641/page-28#post-1104872
https://www.assettocorsa.net/forum/...os-and-acc-vr-about.61513/page-2#post-1104822
https://www.assettocorsa.net/forum/...os-and-acc-vr-about.61513/page-2#post-1105020
https://www.assettocorsa.net/forum/...0-to-rtx-2080-super.63683/page-2#post-1129745
https://www.assettocorsa.net/forum/...0-to-rtx-2080-super.63683/page-2#post-1137909

Disclaimer this is valid for 1080ti / 2070 and faster like performance GPU's, fast CPU/GPU combo needs fastest RAM lowest latency kits available, mid range aren't benefiting as much, spend your money wisely, fast RAM kits are to squeeze the last bit of performance from fastest CPU's and GPU's.

 

How the hell do you get such high average fps at 1440p, what are your settings?

 

It is ofc very dependent on the replay file. I just do it consistently on the same one.

Shadows are reduced by this mod in engine.ini file ( %localappdata%\AC2\Saved\Config\WindowsNoEditor\Engine.ini ) note it is not recommended to modify it

[ConsoleVariables]
r.LightFunctionQuality=0
r.ShadowQuality=0

and my settings are attached below ( paste in %userprofile%\Documents\Assetto Corsa Competizione\Customs\VideoSettings don't forget to remove the frame cap)

 

Okay, cool, will check it out. What do you mean dependant on replay file?

 

Replay files can be limited in quality from the general options (iirc), so it might not be as hard as EPIC settings if so e.g., and also the amount of cars, the weather conditions, the selected track can influence greatly the fps

 

Okay, will have to look into that, does that affect gameplay fps or just replay fps?

 

only the replay FPS afaik, it's hard to mesure the impact on gameplay fps anyway as it's hard to make a perfect A/B comparison. But my point was if you set your graphics to EPIC to benchmark using a replay recorded with MEDIUM settings you won't get the EPIC load as the replay will be limited. But at this point it's an assumption from me, I haven't made A/B comparisons, that's just my understanding of the feature.

 

Okay gotcha, will have to have a play around with this, cheers

 

I only use a 6700k @4.5 four cores, 1080ti @100% cpu 50/60% ????

 

Looks to be limited by GPU as it is on 100%.

 

I've checked also multiplayer performance. Same situation. Also upgraded RAM and no improvement. It looks to me GPU bound. The triple screen configuration is more demanding from rendering point of view.

 

Hello there ! I know the post is old but it is really related to my situation.

I've recently decided to start (finally) simracing on PC and try something different from what I was used to on console. I bought AC and ACC on steam and I began some tests on my triple screens (5760*1080 TV) to see if my hardware could handle it (core i5-8400 + 32Go DDR4 + EVGA 1080 Ti). Even though I was able to tun AC at maxed settings way above 60 fps I realized quickly that my processor was at 100% when testing those games and running ACC was more complicated.

Test scenario : Quick Race / 29 opponents @90% / Nurburgring GP @CLEAR weather

#UPGRADE 1
I didn't want to change motherboard / memory this is why I bought the best processor compatible with my hardware : an Intel Core i9-9900K. The load went from 100% to 20%-30% in my test scenarios so I was very happy that it wasn't my bottle neck anymore. I began my tests again to find the best graphics settings and I realised that now, the bottleneck was probably my 1080 Ti because I couldn't go really further than Medium setting (popping shadows, 16 cars only at a time, a mirror view from another time etc...).

#UPGRADE 2
After a lot of hesitations, I decided to buy an RTX 3080 Ti FE (probably in the worst context ever...) so I could finally play in EPIC settings on my triple screens . I installed everything today and guess what I have nearly the exact same result than with my 1080 Ti ! At first I though that perhaps I had a problem with my power supply (750W) but no, I decided to uninstall / re-install the nvidia drivers but nothing changed ! I still have an AVG of ~90 fps with the same Low 1%(~65 fps) and Low 0.1% (~55fps) with my medium settings the only difference is that now my GPU is at 45-50% load. My CPU is still at ~30% and I've checked all the core and none of them seems to be fully loaded (the main seems to be around 70% of load).

As seb 6th gear said, my 9900K and/or my memory sticks are the problem ? (even though I can't see one of my CPU core at 100%)
With which CPU / RAM can I expect to double my fps and use the full potential of my 3080 ti ?
Is it even possible to reach 180 fps on medium settings with this game ?


PS : As I play on TVs, I need to use VSync this is why I target a low 0.1% above 60fps when I run my tests

 

The CPU in itself isn't the issue, but CPU and RAM are deeply correlated, especially with slow RAM, because 2666 c16 is 12 ns true latency when a "sweet spot" kit rated at 3600 c16 is 8.33 ns true latency.

If your RAM isn't fast enough, your CPU will waste cycles waiting for data, so your CPU usage will be lower than it could reach, your high end GPU won't be fed by the necessary data to process more frames, so GPU cycles will be wasted as well.

That's for graphics, but ACC also uses other threads for sound processing, for physics, for AI, and if your RAM is bottlenecking your system, threads are waiting for data, waiting for other threads to provide data, and some people end up saying "ACC is poorly optimized"... I'm not saying you do, it's just so you get the idea.

upgrade your memory that should help a ton.

before you do, run CPU-Z and check the memory tab it should be half the frequency of your kit rated speed (so 1333) if you are at 1033 you are at JDEC speeds, try to activate the XMP profile that should start to help.

 

Thank you so much for your answer. Playing with CPU-Z and memory timings was a long time ago for me but here it is :

 

The good thing your RAM is used as it should, the XMP profile is set. The "bad" thing it's a slow kit still.

Maybe you could try to see if a friend of yours have a better ram kit and you could try it on your computer, don't forget to make the same check with CPU Z to compare the XMP profile in the SPD tab and the profile active on your computer on the Memory tab.

If you like the improvement, you know you can make a memory upgrade. A 3200 c14 kit would be a very good upgrade, a 3600 c16 kit even better. Both solutions are pretty easy to run (unlikely of 4000+ kits that are way out of memory controller specs on the CPU)

 

Thank you again for your answer @seb 6th gear , I was checking for better ram kits unfortunately my motherboard can't handle more than 2666Mhz and I don't think that 2666MHz CAS11 exists (to reach the 8ns).

The only solution is to go for a new CPU / RAM / Motherboard but I have doubt about the result. If I'm doing all this to gain 10% fps...
My only question is : is it possible to run this game @4K (or 3K in my case) in EPIC settings (and no custom settings etc...) @120 fps rock stable with 30 AI cars and bad weather ?

 

My bad haven't read your signature earlier, I 100% assumed you had a Z chipset board with your 9900K, you're indeed right, no memory OC on older B series chipset, you're limited to official supported specs aka 2666 Mhz... Thank you Intel.

 

Not sure if better hardware is the solution, I think it may be optimisations required. I get the same issue with the kit in my sig.