Broken FPS when threshold is reach (CPU limitation)

[mastah]

As soon as my game reach a threshold in FPS, the CPU goes basically fubar and make the game stutter and drops frame like crazy ...

It's probably the same problem that is causing VR to be unplayble. The CPU load is so much that it's causing crap stutter and frame drops like mad.

I don't play this game anymore in 2D, but fixing the game to 100fps managed to get around the problem for 2D flat screen (not solving the issue, the issue is the game engine).

We now have two limits in DCS : we can't reach high FPS because it's so mono-threaded that the CPU die, and when the CPU die because it has to render twice (VR) the game is basically perma fubar.

Now would be a great time to push the improvement in multithread/multicore. It's starting to be more than urgent. The game keep consuming more and more and been broken in multithread, yet CPU have stopped been more and more performant in single thread and have switched to more core. (Okey time to time there is improvement in IPS but it will be less and less).

A video captured showing the problem (00:26 mark - start of the problem) :

 

It has been captured on 5950X and 3090. Hardly can do better.

[speed-of-heat]

looks like thermal throttling ...

[Boosterdog]

I found DCS has a 200fps cap on my system. No thermal throttling on my end. 

 

[mastah]

2 hours ago, speed-of-heat said:

looks like thermal throttling ...

Dude my whole system is custom watercool, with less than 65°C max temps.. stop guessing what other reports.

The temps are on Tdie, and either intel or AMD goes above 85-90, while the CPU package is at 60-70. RivaTunner is bugged on AMD Zen3 CPU, it affect a single Tdie temps to all other CPU cores. One core is at 85, while the rest are at 50. That's how modern Zen3 works to boost.

Hence why you see 85-88 on all core.

1 hour ago, Boosterdog said:

I found DCS has a 200fps cap on my system. No thermal throttling on my end. 

 

Not sure it's 200fps. I think it's more related to increasing FPS increase CPU usage, and when you reach 100% of the said single core, you can't go higher which imply lots of stutter.

It it was just a hard limit of 200FPS we would have a stable 200FPS. What happen here is the GPU can do 250 for exemple, ask the CPU to render that fast, CPU can't handle, frame are dropped, CPU goes lower, GPU ask more, .... and loops.

I can reproduce the same problem on heavily multithreaded game, by only allocating 1 core to the said game. The FPS will stutter like crazy, because the GPU is too powerful and ask more than the CPU can do.

Edited December 31, 2021 by mastah

[Boosterdog]

2 hours ago, mastah said:

Dude my whole system is custom watercool, with less than 65°C max temps.. stop guessing what other reports.

The temps are on Tdie, and either intel or AMD goes above 85-90, while the CPU package is at 60-70. RivaTunner is bugged on AMD Zen3 CPU, it affect a single Tdie temps to all other CPU cores. One core is at 85, while the rest are at 50. That's how modern Zen3 works to boost.

Hence why you see 85-88 on all core.

Not sure it's 200fps. I think it's more related to increasing FPS increase CPU usage, and when you reach 100% of the said single core, you can't go higher which imply lots of stutter.

It it was just a hard limit of 200FPS we would have a stable 200FPS. What happen here is the GPU can do 250 for exemple, ask the CPU to render that fast, CPU can't handle, frame are dropped, CPU goes lower, GPU ask more, .... and loops.

I can reproduce the same problem on heavily multithreaded game, by only allocating 1 core to the said game. The FPS will stutter like crazy, because the GPU is too powerful and ask more than the CPU can do.

 

Yes you are right. Its not a 200fps hard cap. The more I increase the graphics and the slower the fps climbs on a spike the higher maximum fps I can get. There is certainly something amiss though and its not a system thing.  

 

[G-RUST]

Dude, you video clearly shows CPU temps in the mid 80s

[Boosterdog]

I did some more experimenting. Seems a cap - any cap n the NCP- prevents my frames from crashing - even as high as 300 is fine. Remove the cap and a drop to 50 fps is guaranteed. 

[mastah]

4 hours ago, G-RUST said:

Dude, you video clearly shows CPU temps in the mid 80s

Dude I've explain the reason, maybe you could read ?!