Question Can someone explain CPU usage in 4k to me? And why it's so little?

[Joe_182]

Hello,

I have always heard that the CPU is not super important when gaming in 4k and the GPU does all the heavy lifting. And in my experience, this is what I have noticed. But I am not sure exactly why this is the case? (It would be nice to understand on the hardware level why this happens)

I am using a 12400 with a 4070 super for example, and in Final Fantasy 7 Remake the GPU maxes out at 100%, at 115 FPS, but my CPU is only at 4% usage....Is my CPU really only using 4% of its capacity with lots more available? And does that mean if I were to pair the 12400 with a better GPU like an RTX 5080 it would have enough to keep up with it?

At 4% it seems like I would have a lot more headroom for a better GPU, but looking around lots of people are saying my 12400 would bottleneck the 5080 even in 4k despite only using 4% currently with the 4070 super? I just am not totally understanding the CPU relationship here and how it pertains to 4k, I am clearly missing something....

Thank you in advance

 

[Lutfij]

This reddit post would be a nice way of putting it, to answer the question in your thread title. Have you taxed your platform with other titles, beyond Final Fantasy 7 Remake?

 

[Joe_182]

This reddit post would be a nice way of putting it, to answer the question in your thread title. Have you taxed your platform with other titles, beyond Final Fantasy 7 Remake?

Thank you, I will give it a read. I haven't yet. I don't play too many games tbh. A lot of older stuff for the most part. Fallout 3/4, Skyrim, Mass Effect, Rocket League, etc with some newer stuff sprinkled in.

The most recent games I would care to play are the following off the top of my head

Cyberpunk
FF7 RM and Rebirth
Starfield
Sekiro
Ghost Of Tsushima
Senua Hellblade 2

Cyberpunk is really the only heavy hitter and starfield, and I will be using DLSS no matter what on that game anyway. I think I was getting 70-80 FPS with DLSS Quality with my current setup for CP. It's been a year can't remember tbh. I just dusted my PC off after moving and am trying to just spruce it up a bit now that the 5080 is coming out.

Just not sure if it makes much sense to upgrade my CPU right now or if the 12400 will do just fine with the 5080? Don't want to spend money if I don't need to. (I can get a 12600k for about $70 as an upgrade but it's not really much of an upgrade)

 

[gamerk316]

It's not the CPU doesn't matter; a CPU is doing at least a little more work in 4k then in a lower resolution. The thing is, the GPU has to do almost exponentially more work relative to the CPU, and thus becomes a much larger bottleneck.

 

[geofelt]

Simply put, the cpu generates frames, and the graphics card presents them.
If the gpu is 100% busy, that is your limiting factor.
But, the cpu may not be too far behind.
Be careful how you interpret task manager cpu utilizations.
Windows will spread the activity of a single thread over all available threads.
So, if you had a game that was single threaded and cpu bound, it would show up on a quad core processor as 25%
utilization across all 4 threads.
leading you to think your bottleneck was elsewhere.
It turns our that few games can USEFULLY use more than 4-6 threads.
4% total cpu utilization corresponds to close to half of a single threaded app on a processor with 12 threads.
Activate task manager while gaming. Select the logical view of cpu performance.
I will show you how many threads are used, and how heavily.

You can try a simple test:
Run YOUR games, but lower your resolution and eye candy.
This makes the graphics card loaf a bit.
If your FPS increases, it indicates that your cpu is strong enough to drive a better graphics configuration.
If your FPS stays the same, you are likely more cpu limited.

 

[drea.drechsler]

More simply put: at 4k there are MASSIVELY more pixels in each frame that need color values calculated for them. That's what the GPU does so it's workload logarithmically increases with each resolution bump .

CPU workload is also increased but it's closer to a linear increase. And this has been true for a couple of gaming tech iterations, really since 720p, and even more so since ray tracing which is 100% GPU bottle necked. At the same time CPU's have grown way more powerful with multiple cores/threads that are mainstream and multi-threaded games that can better utilize those cores fairly common.

Probably over-simplified, but not so much it can't help make sense of it.

 

[logainofhades]

Something you may want to watch.

View: https://www.youtube.com/watch?v=98RR0FVQeqs

 

[geofelt]

Something you may want to watch.

View: https://www.youtube.com/watch?v=98RR0FVQeqs

The premise is interesting.
Do you have reference to such information that is not video based?
I do not have the patience to sit through 20 minutes of video.
Text, charts, and benchmarks seem easier to go over repeatedly and analyze.