GPU vs CPU performance

[edmuss]

Hi, not a bug but seeking information and peoples opinions regarding gpu vs cpu performance, apologies if this is in the wrong place

Currently system specs are: -

Ryzen5 3600@4.4ghz all cores
GTX1070 @2100 core / 8900 ram
32gb 3200 ram
Reverb g2
DCS and windows installed on intel pcie nvme ssd

I only recently purchased the g2 as an upgrade from my lenovo explorer so I'm now testing to achieve the best balance of clarity and performance.

Using Kegetys/speed-of-heat shader mods and openvr fsr@0.75 render target, reverb @ 60hz to allow motion smoothing to do it's thing.  I just don't have the horsepower to keep it above the 60fps that wmr needs to motion smooth at 90hz.

On the VR preset with the reverb @ 60% I can get 18-24ms frametimes, motion smoothing pegs it down to 30fps and it's super smooth, GPU usage is about 65%.

I increased the graphical settings to try to maximise GPU utilisation and ended up with most things on high, frametimes went to 21-26ms (still smooth) and GPU usage got up to about 75%.

Increased the steamvr resolution up to 80% and on my custom preset and frametimes are now 24-30ms, usage is up to 90-95% and generally it's all pretty good except for occasional frametime spikes (such as having TGP and MAV screens active) to 32ms which kicked motion smoothing off.

Dropped back to 72% resolution and personally I'm quite happy with it as the frametime stays below 30ms, it's smooth, no stutters and clarity is good, I can read numbers on dials without having to lean in.  Get up above the clouds to 25000 and it's running 24ms.

Through all of this CPU usage is 30-45% give or take and CPU frametimes range from 9-13ms; only using the A10CII easy instant action as a quick and dirty benchmark so I'm fully aware that busier scenarios will pull more CPU overhead out of it. Running the A10 take off training mission gave 33ms frametimes on the runway, changing clutter/tree visibility/scenery detail didn't affect this at all so I think this is a CPU limitation.

VRAM is sat at 6.8 gb for medium/low textures and 7.8 for high/high textures. GPU never gets above 65°C and CPU never above 50°C.

Given all of the above, my question is, will a GPU upgrade actually make a significant difference other than perhaps being able to jump up to 90hz or stick at 60hz and push the resolution up to 100%?

I don't think the CPU is bottlenecking it on the whole and I know I can easily outstrip the GPU with the reverb.  I have no capacity to buy a 3080/3090, I could manage a 3070 (the lad would get the 1070 for his rig) but would I realistically see much of an improvement?

[speed-of-heat]

When measuring  frametimes in vr always turn of motion smoothing , it gives a better indication of what’s going on and how much headroom you have. 

cpu utilisation is a very misleading number… the game puts a lot of emphasis in functionally a single core with some lower performance impacts across a couple of additional threads. So your Ryazan will have 6 cores and 12 threads. So with 30-40% cpu utilisation seems about right.

to your question yes upgrading your gpu  will improve your ability to drive some eye candy, depending on the gpu, but even a 1080ti will provide a significant performance improvement. I moved from a 1070ti to a 1080ti and got an uplift on my old Samsung Oddy Plus, which had a much lower pixel count than the g2.

the question really is what card could you get… in the current market…

[edmuss]

I've been running vrfps alongside the DCS fps counter to work out what's going on, admittedly with motion smoothing on; I'll do some testing with it off.  I'm aware that DCS is largely single threaded, familiar with the issues from arma3 in the past and using solidworks at work, it's numbing to watch 85% of your processor idle while you wait for the blue circle to stop spinning!

I reinstalled windows last night, an update had been repeatedly failing which was in turn preventing the version upgrades, I was still on 2004 but now up to 21H1.  Frametimes seemed to be slightly higher than previous but that's not to say that I haven't missed a setting in the changeover.

I'm keeping a watch out for when the 3060ti / 3070 FE come back into stock, I could sell my 1070 on to make back at least half the cost but I think I'd rather give it to the lad for his machine, he just bought himself a Q2 with his birthday money but his current GPU is nowhere near capable of running link.

As a test I ran a create fast mission with medium forces across the board which smashed hell out of the CPU frametimes up to around 45ms; I don't know if this is typical, I've never actually played with the mission editor before but to be expected I would imagine.

[Walshtimothy]

14 hours ago, speed-of-heat said:

When measuring  frametimes in vr always turn of motion smoothing , it gives a better indication of what’s going on and how much headroom you have. 

cpu utilisation is a very misleading number… the game puts a lot of emphasis in functionally a single core with some lower performance impacts across a couple of additional threads. So your Ryazan will have 6 cores and 12 threads. So with 30-40% cpu utilisation seems about right.

to your question yes upgrading your gpu  will improve your ability to drive some eye candy, depending on the gpu, but even a 1080ti will provide a significant performance improvement. I moved from a 1070ti to a 1080ti and got an uplift on my old Samsung Oddy Plus, which had a much lower pixel count than the g2.

the question really is what card could you get… in the current market…

I've a 2080 and a 2080ti I've been thinking.of selling for a while make me an offer

[edmuss]

Ah if you can offer three year warranty and 3070 FE msrp for the ti then possibly?

Keeping a very close eye on the FE stock alerts at scan!

[pixie]

On 11/8/2021 at 11:32 AM, edmuss said:

 

Given all of the above, my question is, will a GPU upgrade actually make a significant difference other than perhaps being able to jump up to 90hz or stick at 60hz and push the resolution up to 100%?

I don't think the CPU is bottlenecking it on the whole and I know I can easily outstrip the GPU with the reverb.  I have no capacity to buy a 3080/3090, I could manage a 3070 (the lad would get the 1070 for his rig) but would I realistically see much of an improvement?

My answer is a short one : definitely yes, go for it !

I had the exact same specs Ryzen 5 3600, 32GB and GTX1070 and discovered VR with a Quest2. I have since upgraded to an RTX3060TI FE which is in the 3070 ball park. This was a great improvment. I have no solid data nor FPS logged to prove my point, but even if I got badly scalped in the process, this is an upgrade I will never regret. You know as well as I am that when you have tasted VR simulation there is no turning back. A 3070 will give you the much need headroom to tune your VR settings. 

[Morat]

Even a 3080 won't max out a G2. I'm thinking of it as good news, because my HMD is good for another generation. Glass half full, and all that.

[lefuneste01]

It's impossible to get 90 Hz every time due to poor CPU usage parallelization. And you will also find some difficulties to maintain 45 Hz in every time, to allow reprojection with 90 Hz. So 60 Hz is a good target. A better GPU may increase the time for which you will be able to have these 60 Hz, if CPU is not the bottleneck.

[speed-of-heat]

I'm not seeing that most of the time i am GPU bound...