Bottlenecking Technical Clarification

[Shadaz]

Hey guys,

 

I am new to this forum, so any advice will be greatly appreciated.

 

I am currently running a 5 year old pc build consisting of-

 

i7  4770K ( edited from 4700K)- Overclocked to 4.4ghz

Gigabyte GTX 780 OC

Kingston HyperX  16G kit DDR3 1600 RAM

 

I am planning to upgrade my rig to specifically play Battlefield V on a 144hz 1440p monitor.

 

I was planning to purchase a GTX 1080ti or sli config for this and was wondering if my cpu would be a bottleneck?

 

I am also curious, for future understanding on how CPU bottlenecking actually works.

 

This is my understanding please clarify if this is wrong-

 

The GPU with a certain resolution, graphic settings sends x amount of frames to a cpu to process if the CPU is good enough it will process all the frames if not the frames will be lost.

 

I was recently watching this video

 

https://www.youtube.com/watch?v=Oc08ZPc30Zs

 

 At 4:54 we see that the i7 8700k can process a max of 199 FPS.  Whilst the I7 4770K can process a max of 153 fps.

 

So to my understanding irrespective of the setting/ resolution. If a million frames Ultra setting 4K frames  was sent to the CPU, it would only be able to process 153 FPS average in BF1 ?

 

Am I correct with this understanding.

 

Also if the GPU utilisation is very high i.e 90% + does that mean the CPU is not bottle-necking the GPU?

 

Thank you all for your help

 

 

[Cereal5]

 

34 minutes ago, Shadaz said:

i7 4700K

This is not a CPU. The 4770K and 4790K are though.

34 minutes ago, Shadaz said:

The GPU with a certain resolution, graphic settings sends x amount of frames to a cpu to process if the CPU is good enough it will process all the frames if not the frames will be lost.

 

That's backwards. The CPU is the source of pretty much everything. The CPU sends the GPU frames to render. If the GPU is fast enough, the CPU will not be able to send enough frames to the GPU to keep it busy, thus creating a CPU "bottleneck" (see below for in-depth explanation).

 

34 minutes ago, Shadaz said:

So to my understanding irrespective of the setting/ resolution. If a million frames Ultra setting 4K frames  was sent to the CPU, it would only be able to process 153 FPS average in BF1 ?

Apply above logic, but basically yeah. The CPU can only send so many frames to the GPU, so even if the GPU could theoretically render 1000 frames in one second, the CPU will restrict it to x-amount (again, see below for in-depth explanation).

 

34 minutes ago, Shadaz said:

At 4:54 we see that the i7 8700k can process a max of 199 FPS.  Whilst the I7 4770K can process a max of 153 fps.

It is unclear what the usage of the CPU is in this video. Around 80% constitutes a high likelihood of a CPU bottleneck. However, we can assume this is not the case, because even when comparing two baller CPUs like the 8700K and 2700X, neither will get even close to that, while GPU usage is still at 99%, and there will still be a difference in frame rates. The difference in frame rates here (and when comparing the 4770K and 8700K) comes from architectural and Instruction per clock (IPC) differences. Current gen Intel CPUs have an advantage in both (however big or small it may be), and this allows the CPU to execute all commands faster, not just games. This allows more time for the CPU to spend sending frames to the GPU, for it to render on the screen, which results in higher framerates. There is no CPU bottleneck with either CPU, but there is a difference in frame rates. This is important to remember when comparing old hardware to new. Even if you get better frame rates on better hardware, that doesn't mean there is a bottleneck with old hardware. The reverse of this is just because you upgrade your CPU, that does not mean always you will get better frame rates, if there was no bottleneck to begin with

34 minutes ago, Shadaz said:

I was planning to purchase a sli config

Do not use SLI, ESPECIALLY on 4 generation old hardware. Even on current gen hardware, it's arguably not worth it. This is another discussion though, and there are plenty of threads that explain why, so I will not.

 

 

If all else fails you, here's a video, although I encourage you to read it all since I put some time into this answer lol

 

[Shadaz]

Thanks a lot for the in-depth reply. I have had a thorough read of what you have written and  watched the video provided.

 

It states bottlenecks can be minimised but not eliminated. 

 

My goal is to get every cent out of my graphics card, ie that be the bottleneck of the system. Upon your recommendation I am looking at the GTX 1080 Ti right now. Will my CPU, I7 4770k OC at 4.4 ghz be a bottleneck for the GPU?

 

 

Moreover, you mentioned how newer hardware has better architecture and IPC. So I would be getting less frames the these benchmarks even if my 4770K is not a bottle-neck? 

 

The test rig had a setup of a  Core i9-9900K clocked at 5 GHz with 16GB of DDR4-3400 memory. 

 

 

 

 

Also, to clarify your point about how frames are rendered.

 

So the CPU is like, in this game. I can process 150 FPS max.

 

But if the settings is Ultra at 1440p and you get 100 FPS, it means the GPU can only render 100 of those 150 FPS. It means the GPU is the bottleneck? 

 

 

 

I am finding this really interesting and would love further clarification.