Refresh Rate with different monitors

[Bill A 68]

Hi all, I have a question on refresh rate. I have my main monitor which can go to refresh rate of 75, then I have my side monitor that has my flight plans and other tool. Now that monitor can only go to 60. Is the best to set both of them to 60, or keep the one that is used for flight SIM for the actual flying at 75? Watch many videos on the proper settings for NVIDIA and have my frames locked at 30 on flight Sim and some are telling me to set thru the Nvidia CP 75 for the frames, or even 2 frames lower than the refresh rate for example 73. I do notice if I lock to 75 the frames via CP, I can't lock to 30 in the sim even though I gave 30 set in the flight sim.  Now here is the catch, if I set the monitor refresh to 60 then I can lock the frames in the sim at 30. So I'm kinda lost as why I can' lock the frames are 30 when set a refresh of 75. Plus I use track IR and when panning the frames never drop but it's not very smooth, it's like there are little mico stutters. Idk.. just needs some tips. 

[MrFuzzy 2,117]

If you lock your framerate at 30 fps, keep both monitors at 60 Hz. You will never reach 75 fps anyway.

You should be able to lock your framerate to 30 fps also at 75 Hz refresh anyway. Try RivaTuner.

In case you set "30" in the sim with a refresh rate of 75 Hz, the framerate will be locked to 37.5 (half of the refresh rate)

I'd keep 60 and 30, as for TrackIR if you pan the view rapidly it won't be smooth with only 30 fps anyway... it's all a matter of compromises until the hardware will be able to deliver 60+ fps consistently.

Edited August 7, 2022 by MrFuzzy

[RJC68 820]

I’ve done lots of testing on the new PC I just built and I find the best results are with Vsync set to “On” in Nvidia Control Panel then lock the frames with Riva tuner as I can adjust on the fly depending what I am flying. For instance in complex aircraft such as Fenix or PMDG I just find better results sticking to 30fps, what I find helps with panning in the cockpit is in the camera settings turning the momentum slider to zero and increasing the speed a little. But the biggest thing you need to do when choosing your settings is make sure you are always GPU limited. In the FPS window in developer settings if you are locking to 30 fps try and get the GPU timing to around 30ms by adjusting the graphic settings. On my system I can run everything on Ultra and but what I didn’t realize was that my CPU & GPU timings were similar and sometimes I would become CPU limited for split seconds which could introduce stutters. As all of my graphic settings were maxed out I actually increased the render scale to increased the load on my 3080TI. I am running the sim in native 4K and by increasing the render scale to 130 I saw my GPU timing sitting around 25-30ms with my CPU timing around 18ms. I use the onscreen display in Riva to monitor hardware performance and what I noticed was by keeping the GPU timing higher than CPU (you always want to be GPU limited) is that the frame time graph was perfectly flat. Doing this makes sure your CPU always has headroom when passing frames to the GPU to be processed and results in the best chance of a fluid experience.  If you need to lower the CPU timing at all play around with the LOD sliders and traffic. 
 

Running at 60 fps in say the TBM it is a little more challenging to get the GPU timing as far apart from the CPU as I mentioned above. The key is always being GPU limited. This is the first time I have tuned the sim this way and it does make a difference.

[Ianrivaldosmith 5,317]

So, you’re running at 10.3 million pixels roughly? Wow. My 3090 can’t even handle that. 

[RJC68 820]

2 hours ago, Ianrivaldosmith said:

So, you’re running at 10.3 million pixels roughly? Wow. My 3090 can’t even handle that. 

If you we talking about my post Ian then I guess so.

I find that for the PMDG & Fenix using the approach above I get a better experience in the sim. Because I’m limiting the frames at 30 the GPU has head room and by pushing the render scale to 130 only took it to around 70% utilized but more importantly I’m never Main thread limited. I did some experimenting last night with the 737-600 locking the frames to 60, it is doable but I have to dial back some of the settings a fair bit. The procedure I described above is the same for however you run the sim, the key seems to be utilizing the power of these modern GPU’s to ensure we’re never main thread limited. Push whatever you can to the GPU.
Apart from the extra VRAM our cards are essentially the same so there’s no reason this wouldn’t work. I know panning in the cockpit isn’t quite as smooth but I’ve found speeding up the camera to 60 and reducing the momentum to 0 helps. 
I just finished a short test in the 737-600 from Aberdeen to Newquay with every setting to the max and TLOD & OLOD on 200 and the frame time graph was basically a flat line the entire way with live weather and real time on line traffic. 

[Glenn Fitzpatrick 3,798]

The relevant number to look up is not the maximum frames it is the minimum the monitors can handle without resorting to gsync/freesync .