Reducing refresh rate to 72Hz in SimRacing games results in a 25% performance boost while keeping it smooth

The original title was:
“A temporary (but free) alternative to the expensive 2080ti->3090 conversion :25% performance boost (pimax)”

(It has been edited by a mod I guess, for more clarity)

This is especially for simracing guys who use to play at the 90hz mode (Normal or Large fov), but it could also work for other kind of games.
No big secret here, nothing revolutionary.
Just something I wasn’t expecting and that changed my mind about the possible use of a 8kX for sim racing.
I use to play Assetto Corsa on my 5k+/2080ti (no parallel projection needed, well optimised for VR, good simulation, tons of content)
After being hooked by the 144hz mode with smart smoothing, (because it was so smooth), I noticed that without smart smoothing, it dropped sometimes to the 90 FPS area, and at 90 FPS it was jerky/stuttering.
This gave me a bad opinion about the 90Hz mode.
Then, because I wanted to test Large mode, I tested the 90Hz mode.
With pitool 1, 202% Supersampling, I managed to have a solid 90 FPS, and found out that finally 90FPS on 90Hz is also very smooth ! and the Large mode is a no brainer for sim racing (immersion ++; sens of speed ++)
But with Content manager+shader patch+SOL, it’s GPU demanding. it’s ok most of the time but if I put more than 16 cars, or on certain track mods, I have FPS drops, and get something in the 72-75 FPS zone.
And at this FPS, this is stuttering.
So this gave me a bad opinion of the 72hz mode for sim racing (because things are moving fast, it needs to be smooth).
You see me coming?
I finally tried the 72 HZ mode (which also has got the Large FOV), of course I was expecting a jerky experience, but the contrary happened !
I had a very solid 72 FPS on the 72Hz mode and after hours of tests on different tracks, with different cars, I found it smooth as hell ! I didn’t believe my eyes. honestly, in the end of the day I couldn’t see any noticeable difference with the 90 Hz mode (according to my memory of it), and believe me I looked hard.
Not only that but now I can put 24 cars and have a smooth and stable experience, no matter what, and this is in Large FOV.

Here is the irony :
90 FPS can be a stuttering mess (if it happens on the 144hz mode), while 72 FPS can be extremely smooth (if it happens on the 72 Hz mode).

Let’s resume,
-without smart smoothing, If you have less FPS than your refresh rate, you’ll have a jerky experience.
-If you have has many FPS as your refresh rate, the experience is smooth.
-a solid 72 FPS on 72Hz mode is smooth enough for sim racing, (tested at very high speeds, and on all kind of race conditions).
-72 FPS is 25% less frames per second to render than 90 FPS, hence a 25% performance boost that you can use for more cars, more SS, or more visual quality option.

Maybe if you go straight from 144 hz/144FPS to 72 Hz/72FPS, you’ll see a difference in the first place, but my point is that the 72hz mode is way smoother that what I expected, and more than enough for sim racing.

This is why the idea of a 75HZ max framerate on the 8kX in native resolution doesn’t bother me anymore when it comes to sim racing, as soon as you can get a solid 75 FPS.

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All I do in vr is ac and mine runs locked at 120hz. I can do 144 as well but seems to have more distortion on the edges. Tuning your memory, maxing out your core and uncore helps a ton.

120 - 144 is a lot smoother. No smart smoothing or anything. Just hidden area mask enabled.

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What are your specs?
GPU, pitool quality, total SteamVR SS, 5k+/8k+, Shaderpatch+lightFX+SOL ?

Like I said, I used to play on 144hz, also used the 120 hz, but it excluded to use the Large mode, and at this time I was adding more and more SS to have a clear image. and if I planed to use the SOL and LightFX apps on the Content Manager, then I had to reduce the supersampling, and/or only put a couple of cars on the track, or I couldn’t even keep the smart smoothing consistent, let appart reaching a pure 144 FPS. and this is on a 2080ti
But at this time I wouldn’t have believed that the 72hz mode was smooth… until I tried for hours.
Turns out it IS smooth, and lets me play on large mode, without smart smoothing, with a decent 202% Supersampling (4828x2980 if I remember well), all the SOL+lightFX options, and a buch of cars in the track.
There’s no way I could reach all those specs on higher refresh rate mode, unless I use smart smoothing again (which isn’t as nice in 72hz as in higher modes)

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9900k 52x core and 48x uncore. All power limited removed. HT off since it causes regression

Mem is fully hand tuned and helps a lot in low fps which is what the stuttering is. Along with CM settings:

PiTools = 1.0x SteamSS 160% 120hz and the highest fov available. I couldn’t notice any visual quality gains after 160% personally.

Nvidia control panel: 16x AF forced, Negative LOD Bias = Clamp. Texture filtering = high quality

I only race online so this includes racing with others. Not just hot laps.GPU is a 2080ti around 2000 core sustained in long sessions.

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Impact of CPU/MEM/HT:

This is using the capframex and the built in benchmark.

my i710700 is OC, so is my 2080TI, 32 Go 3200Mhz but I never twitched the HT thing yet.
how do you turn the HT off?
Now with a 160% SS only and using the normal FOV, you naturally get a chance to get a constant 120 FPS.
what CM app do you use? (LightFX, SOL, other? ) some of them are more GPU demanding.
I’ll try to get the SS down to 160% to see if I see a difference with 202%
Thanks

You disable hyper threading in the BIOS. I don’t run post processing filters. My first priority is clarity and locked frame rate as competitive racing is the first goal. It’s the main reason I’m moving to a G2. I want the distance clarity to pick out my points better.

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For people who want to see how incredibly smooth 72hz actually is, try Air CAR, in large mode.
this is a FREE little game on steam.
you are in a futuristic flying car in a blade runner style gigantic mega town, full of gigantic buildings, with a never ending rain.
you can fly thanks to the two htc vive controllers, the index controllers or a joystick.
it’s incredibly smooth, the 2080ti can reach a solid 72 FPS in large mode without any issue, and it’s very immersive.
you’ll see how extremely smooth it runs on the 72hz mode (at least on the 5k+)
So if your GPU can handle 72 solid FPS on any racing/flying game, it will be smooth as hell in 72hz mode. .
Here is a trailer of Air Car
https://www.youtube.com/watch?v=7O1N9eEPezE

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