What is a "GPU bottle neck"? [SOLVED]

[Reddy]

I'm fairly certain I know what one is, but I'm merely looking for confirmation or the correct answer if I'm wrong.


From what I understand, a "GPU bottle neck" is when the video card can't run at its full potential. Usually meaning that the GPU usage isn't at 90%-100%, but the CPU is at 90%-100% when in a scenario where the frame rate is completely uncapped. Thus, the CPU can't handle any more information from the GPU, so the GPU is being limited.


People are trying to explain this to me saying that "If the GPU is at 100% then it's limiting the CPU to get to 100% usage". This doesn't seem right, as from what I understand, not every program/game, or whatever...will require 100% of the CPU.

For example, let's say I'm playing Grand Theft Auto V. My CPU (i7 4790k @ 4.8GHz) usage is 40-50%, and my GPU (GTX 1080) usage is 99%-100%. I'm playing at 1440p, very high settings, with vsync disabled. According to them, my GPU is limiting my CPU in this scenario.


They also insinuated that you can tell if your GPU is being bottle necked by the CPU just by the frame rate you're getting. This doesn't seem right to me either. To my knowledge, not every processor is the same. There are differences such as IPC performance, amount of cores/threads, etc...and some games will benefit from higher CPU frequencies than they will from more cores and/or threads. This being the case in games such as GTA IV and GTA V. These games being developed on the Rockstar Advanced Game Engine, need to make a lot of calculations and draw calls faster.

Thus, prefering a higher clocked CPU rather than one that has more cores and/or threads. In this case, for example, having a i5 3570K at 5GHz would yield a better frame rate than a i7 6800K at stock speeds...but that's not to say that the i7 6800K is bottle necking (limiting) the GPU from being used to it's full potential.

[Alexalmighty]

a gpu bottleneck is when your gpu is too weak for your system

also when playing games at 2k or 4k your gpu will always bottleneck your cpu unless your cpu is very weak or very old

[Reddy]

Any other answers from any one else? Any one that can read the full OP, and provide sources if making claims different to my own?

[Ocelote.12]

Yes, GPU bottleneck is when GPU is the weakest link.

[Reddy]

Publicado originalmente por Manul:

Yes, GPU bottleneck is when GPU is the weakest link.

Okay so what is the GPU bottle necking in that scenario?

[Alexalmighty]

Publicado originalmente por Feyrom:

Publicado originalmente por Manul:

Yes, GPU bottleneck is when GPU is the weakest link.

Okay so what is the GPU bottle necking in that scenario?

your system basically your computer is waiting for your gpu to render the image

[nullable]

I would worry less about bottlenecks if I were you. Half the people blathering about them don't know what they're talking about and are just repeating nonsense other people are repeating. And you can usually see this when someone posts some hardware and asks about bottlenecks for any arbitrary configuration. People are all too happy to sound off without any data, and entirely relying on their hardware intuition and perceptions of the hardware in questions.

I've spent the last twenty years listening to that nonsense. And on top of that, it doesn't matter if your hardware is being use optimally. It only matters if it performs well enough for the task at hand.

http://www.techspot.com/article/1039-ten-years-intel-cpu-compared/page5.html

I mean granted CPU intensive games suffer a bit more. But GPU intensive games, if you've got a good enough GPU the CPU is very secondary. And seeing how CPU's last for 4-6 years easy these days.

The only GPU bottlenecks I would worry about is if an upgrade is going to get you literally zero performance increase. And that's pretty much never going to happen...

As far as a fantasy of all hardware being used 100% being optimal, those people are just ignorant. Most software or games don't run that uniformly across all aspects of hardware and making them arbitrarily to satisfy some hardware pseudo intellectuals is not a good use of time or resources.

[Reddy]

Publicado originalmente por Brockenstein:

I would worry less about bottlenecks if I were you. Half the people blathering about them don't know what they're talking about and are just repeating nonsense other people are repeating. And you can usually see this when someone posts some hardware and asks about bottlenecks for any arbitrary configuration. People are all too happy to sound off without any data, and entirely relying on their hardware intuition and perceptions of the hardware in questions.

I've spent the last twenty years listening to that nonsense. And on top of that, it doesn't matter if your hardware is being use optimally. It only matters if it performs well enough for the task at hand.

http://www.techspot.com/article/1039-ten-years-intel-cpu-compared/page5.html

I mean granted CPU intensive games suffer a bit more. But GPU intensive games, if you've got a good enough GPU the CPU is very secondary. And seeing how CPU's last for 4-6 years easy these days.

The only GPU bottlenecks I would worry about is if an upgrade is going to get you literally zero performance increase. And that's pretty much never going to happen...

Someone very clearly "sounded-off" without reading the OP. I'm not worried about bottle necks. I just want to clarify what a "GPU bottle neck" is.


Also, just because a zero performance increase from upgrading your GPU will "pretty much never happen", doesn't mean that you shouldn't worry about it when looking to upgrade. I'd much rather not spend $400 to upgrade my previous $400 GPU just for a 10-20fps increase in performance, when benchmarks and evidence suggests that with a better processor, I'd get a way bigger increase of performance, than what I would get with my current processor.

[Ocelote.12]

Publicado originalmente por Feyrom:

Publicado originalmente por Manul:

Yes, GPU bottleneck is when GPU is the weakest link.

Okay so what is the GPU bottle necking in that scenario?

No, the "GPU bottleneck" means that the bottle neck in IN the GPU.

[Reddy]

Publicado originalmente por Manul:

Publicado originalmente por Feyrom:

Okay so what is the GPU bottle necking in that scenario?

No, the "GPU bottleneck" means that the bottle neck in IN the GPU.

Oh, right. Okay, now I understand.

So was everything I said in my original post, correct then?

[Kaihekoa]

Publicado originalmente por Brockenstein:

I would worry less about bottlenecks if I were you. Half the people blathering about them don't know what they're talking about and are just repeating nonsense other people are repeating. And you can usually see this when someone posts some hardware and asks about bottlenecks for any arbitrary configuration. People are all too happy to sound off without any data, and entirely relying on their hardware intuition and perceptions of the hardware in questions.

I've spent the last twenty years listening to that nonsense. And on top of that, it doesn't matter if your hardware is being use optimally. It only matters if it performs well enough for the task at hand.

http://www.techspot.com/article/1039-ten-years-intel-cpu-compared/page5.html

I mean granted CPU intensive games suffer a bit more. But GPU intensive games, if you've got a good enough GPU the CPU is very secondary. And seeing how CPU's last for 4-6 years easy these days.

The only GPU bottlenecks I would worry about is if an upgrade is going to get you literally zero performance increase. And that's pretty much never going to happen...

As far as a fantasy of all hardware being used 100% being optimal, those people are just ignorant. Most software or games don't run that uniformly across all aspects of hardware and making them arbitrarily to satisfy some hardware pseudo intellectuals is not a good use of time or resources.

This guy knows what he's talking about.

@OP: A bottleneck refers to one part of a any kind of system slowing down the whole process. A slow grill cook can be a bottleneck at McDonald's for instance. You have the general idea right, but don't use the term properly in your OP. In your example, you would actually say the GPU is being bottlenecked by the CPU. It would make more sense to refer to that scenario as a CPU bottleneck as that is the slowest part of the system limiting the performance of the whole system. But, as this guy said, the term is extremely overused by gamers who don't know what they are talking about.

[upcoast]

Publicado originalmente por Feyrom:

Publicado originalmente por Manul:

No, the "GPU bottleneck" means that the bottle neck in IN the GPU.

Oh, right. Okay, now I understand.

So was everything I said in my original post, correct then?

Gpu bottlenecking is when the gpu pegs at %100 usage and the cpu isn't pegging at %100.

Cpu bottlenecking is when the gpu like you said before cannot achieve it's full potential ie peg at %100 because the cpu is pegged at %100 and just can't work any faster to keep up with the gpu so the gpu usage plummets to a lower percentage usage like %60-%70 would be considered a moderately bad bottleneck.

Ppl get too hung up on bottlenecking these days and really don't get the concept of ipc being a factor also, if one blue cpu can do more work per cycle vs the cursed red one that doesn't necessarily mean the cursed red one cpu is bottlenecking a gpu it just means that's what it performs at.

TBH I own a few cursed red one cpus and they in fact do not bottleneck in gta 5 they do not peg at %100.

Some ppl actually think all blue cpus won't bottleneck gpus well that would be wrong.

Long and short bottlenecking is over used.

[Reddy]

Publicado originalmente por upcoast:

Publicado originalmente por Feyrom:

Oh, right. Okay, now I understand.

So was everything I said in my original post, correct then?

Gpu bottlenecking is when the gpu pegs at %100 usage and the cpu isn't pegging at %100.

Cpu bottlenecking is when the gpu like you said before cannot achieve it's full potential ie peg at %100 because the cpu is pegged at %100 and just can't work any faster to keep up with the gpu so the gpu usage plummets to a lower percentage usage like %60-%70 would be considered a moderately bad bottleneck.

Ppl get too hung up on bottlenecking these days and really don't get the concept of ipc being a factor also, if one blue cpu can do more work per cycle vs the cursed red one that doesn't necessarily mean the cursed red one cpu is bottlenecking a gpu it just means that's what it performs at.

TBH I own a few cursed red one cpus and they in fact do not bottleneck in gta 5 they do not peg at %100.

Some ppl actually think all blue cpus won't bottleneck gpus well that would be wrong.

Long and short bottlenecking is over used.

Thanks for the clarification, this is the kind of reply I was looking for.


I agree 100%. Thanks again.

[WarmedxMints]

Here's basically how a computer works when running games;

Your CPU processes the frames and sends them to your GPU to be rendered.

A GPU bottleneck is when your CPU is waiting for your GPU to finish rendering frames before sending it any more work. So basically your CPU is ready to send more frames to be rendered before the GPU has finished it's last workload.

A CPU bottleneck is when your GPU is waiting for your CPU to send it more work. So you GPU has finished rendering all the frames from it's previous workload before the CPU has finished processing the next.

As others have said, it doesn't really matter if there is a bottleneck or not as long as you are getting the performance you want from your system. You do read of some people complaining that they upgraded from a 750ti to a 1060 and haven't seen a performance increase in CSGO and are still getting 250 fps. That would be a CPU bottleneck as it wouldn't matter if they bought a Titan XP because their CPU can't send the frames any quicker to the GPU and the GPU can easily render that many fps in that game.

It isn't all black and white though as some game engines are just poorly coded and end up using the CPU to do work that the GPU should do or vice versa. So in some games, even with the most powerful CPU, you will end up with a CPU bottleneck because it is being used poorly.