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CPU's bottleneck Game performace, but NOT the GPU.

There is NO DOUBT the CPU can lower performance in gaming.
Especially in games like Everquest 2, Supreme Commander, or many other MMO's or RTS games.

The argument is not that CPU's don't matter, but that the CPU doesn't bottleneck the GPU and that to say "The game's poor performance is because your CPU is bottlenecking your GPU" is as accurate as saying "The game's poor performance is because your CPU is bottlenecking your DVD drive."

In essence, both of these are true, but also inaccurate and misleading.

It's certainly possible the CPU is overloaded by the game software and thus cannot feed the GPU enough information for it to process completely. In fact, this is very likely because the CPU is busy doing its own calculations while the GPU yawns, waiting to be used in the freeze-ups and lag-fest of entering a contested area.

Of course, the same could be said for the DVD drive, or ANY component. The CPU is overloaded, so it can't feed information to ANYTHING else, such as the DVD drive. Try to access your DVD drive, and you'll be bottlenecked by your CPU. If you're running a music cd, it might stop playing because of the lag.

So to say a CPU bottlenecks the GPU is inaccurate. It's simply more obvious to say "The CPU is bottlenecking your game's performance." it has nothing to do with the GPU!

I have seem one person's link explaining how a CPU bottlenecks a GPU, but this is mostly hogwash in modern hardware. Sure it's a possibility, but not a realistic one. You would have to have a controlled, conditioned experiment with homemade software just to overload a CPU with information to the GPU. In today's technology, although some poorly designed video games tax the CPU a lot in addition to the GPU, modern CPU hardware in relation to CPU Usage vs CPU:GPU information load is vastly superior to GPU hardware in relation to GPU Usage vs CPU:GPU information need. In other words, the GPU tends to be overloaded far more easily than its equal tier CPU (best vs best, budget vs budget, crappy vs crappy) and so a budget CPU could easily be more than enough to run the program in addition to feed the GPU all information it needs, and is only going to bottleneck performance when the software's CPU need is many times greater than the average CPU:GPU need.

For you to be able to prove that the CPU bottlenecks the GPU, you would need a program intensive enough to send the GPU enough information to tax it 100%, and see the CPU usage. Of course, no one wants to do this because the CPU usage would not be 100%, even on some awful processors. In all but the worst of processors, the CPU usage solely from CPU:GPU will be low enough for the CPU to easily also include running other hardware, the OS, and the software and will only be limited by the software's need for CPU usage- NOT GPU usage.

In fact, the only times you will see the CPU at 100% and the GPU lower, is when the CPU is bottlenecked by the game's software. That the game software itself is wanting so much processing power from the CPU, that the GPU doesn't get the information resulting in UNPLAYABLE lag. But most of the time this IS NOT the case. Often the GPU will be working at less than 100% speed or even at 100%, while the CPU is still lagging the game but not unplayable lag. Upgrade the CPU, and the GPU will often still be at the same speed it was before, showing that the CPU feeding the GPU was NOT the bottleneck, but that the bottleneck resulted in the CPU overloading via the game software's demand on the CPU- NOT the GPU.

Hence the expression, "CPU's do not bottleneck the GPU." and said Myth.
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More about bottleneck game performace
  1. I remember I upgraded my graphics card to get better performance out of eq2, and it did not give it to me, I was very sad.
  2. Ok, here's a simple version because you don't seem to understand what you're trying to say.

    A bottleneck is when something slows down something else. Draw a longneck bottle, look at the bottle's neck, and you can see it. If you chop off the neck, you can pour much faster, hence the term: bottleneck.

    In a perfectly balanced system, which includes a perfect balancing of software-load, there won't be a bottleneck. The CPU and GPU (and all other aspects of the system (ie. memory, system bus, HDD, optical drive)) both work full-tilt, neither is being bottlenecked. Both have enough work to use all their resources. If a GPU isn't working at 100% the CPU (or some other hardware) is limiting its performance, this is obvious because if the GPU is running at 50%, it could churn out many more frames/data if it was working at 100%. The bottleneck isn't necessarily that it's not getting enough information across the bus, the bottleneck is usually that the GPU is processing frames/data (significantly) faster than the CPU/other component. The same is true in reverse, with all aspects of hardware affecting all other aspects, even down to low-level cache, cpu/gpu architecture, system bus, memory bus, memory itself, et cetera ad infinum.

    And before you even mention it, yes, it can often ALSO be the fault of software, as a single-threaded program can force the CPU to limit the GPU because it is not actually using the FULL CPU, however, this is still a CPU bottleneck (CPU is at 25% on a quad because it is unable to use its 'spare' 3 cores).

    Do you get it yet?
  3. anarchy4sale said:
    I remember I upgraded my graphics card to get better performance out of eq2, and it did not give it to me, I was very sad.


    Same here.

    When I upgraded from Core2Duo to an i7, I went from 40fps to 60+fps in Everquest 2.


    Later I found out it's because it uses some archaic form of Unreal 1 engine.
    It's so old that it barely even recognizes the GPU :P LOL


    Also, I LOSE 10fps when I turn on CrossfireX. I have to play it on only one card.
  4. You already posted this.
  5. Dekasav said:
    Ok, here's a simple version because you don't seem to understand what you're trying to say.

    A bottleneck is when something slows down something else.


    Yes, and the CPU slows down THE GAME and the ENTIRE COMPUTER, not the SPECIFICALLY the GPU.
    What you fail to comprehend is how it may be true, but is highly inaccurate to say the CPU bottlenecks the GPU.

    Many people believe that upgrading the CPU will result in the GPU getting more work because the CPU needs extra power to feed the GPU. What is reality though is it is because the CPU needs extra power to feed EVERYTHING.

    It's less that it is slowing down bc the GPU can't get enough calculations.
    It's more slowing down bc the CPU can't get enough calculations for the CPU.
    To say the former is misleading and inaccurate, at it describes about 10% of the actual bottleneck. If the CPU bottlenecks the entire system, of course it bottlenecks the GPU- but you don't say that. You say it as any intelligent person woud in an accurate, fully informative way. "The CPU is bottlenecking the entire system and hindering software performance." NOT saying "The CPU is bottlenecking the GPU."

    You are disagreeing with me about my post, and restating everything I already agree with.
    The CPU is the bottleneck of the SYSTEM, but NOT the bottleneck of the GPU specifically.

    To say the latter is to confuse people, thinking they need to get a worse GPU when that won't fix the problem, because the CPU needs power for the CPU, NOT the GPU.


    I'm sorry if the explanation was too complicated for you, but please don't be so arrogant as to explain the definition of a bottleneck to me just because you failed to comprehend the description of hardware design.

    CPU Calculations
    ////////
    CPU ------- DVD DRIVE Calculations
    \\\\\\\\\
    GPU Calculations


    If the Top of that picture, if the software wants more of the top, the ONLY reason the GPU or DVD Drive is bottlenecked is bc the CPU needs more information. It's NOT because the GPU needs more calculations.

    That's as simple as I can explain it to you.
  6. randomizer said:
    You already posted this.


    Troll Fail.

    This is a more mature discussion with technical explanations for adults, so please leave.
  7. nitros85 said:
    The CPU is the bottleneck of the SYSTEM, but NOT the bottleneck of the GPU specifically.

    So your whole argument is over semantics? Ok, fair enough.

    nitros85 said:
    To say the latter is to confuse people, thinking they need to get a worse GPU when that won't fix the problem, because the CPU needs power for the CPU, NOT the GPU.

    People who come to that conclusion probably never read the advice they were given. I don't believe I've often seen someone suggest getting a poorer performing GPU because the CPU isn't powerful enough, the advice is to get a faster CPU.
  8. randomizer said:
    So your whole argument is over semantics? Ok, fair enough.


    LOL Yes...


    The entire thread, topic, and myth is solely and precisely about semantics.
    The thread before this one was also about semantics.

    Education is important, and if people are being taught that the CPU bottlenecks the GPU, it's incorrect. What they need to know is that the CPU doesn't bottleneck the GPU, but it bottlenecks the ENTIRE SYSTEM (which includes the GPU).

    These specifics are important to understanding how hardware and mechanics work. It is in the broad scope of things that we can better understand the more precise details of what goes on, providing for more education in all things related.


    So is this the entire reason people are so argumentative? The way it comes off in my posts is saying "Bottlenecking doesn't exist!" because they do not understand what I'm saying is "The semantics are IMPORTANT, so get it right!"
  9. They said the CPU bottlenecks the GPU. You said CPU bottlenecks the System. The GPU is part of the system... You're both fighting on the same side...
  10. The only immature person here is you Nitros85... how many threads will it take for you to let this syntax argument go? Are you really so needy for attention?
    So what if not everyone wants to explain things exactly like you? You just make yourself look like an arrogant asshole making a big deal out of nothing. Like others have said, learn what bottleneck means.
  11. nitros85 said:
    The entire thread, topic, and myth is solely and precisely about semantics.

    Well I think it would have been good to state this at the start. I do think some people are reading your posts as "bottlenecking is a myth," particularly since your first thread was titled "Hardware Bottleneck is a Myth." :)
  12. We generally say the CPU bottlenecks the GPU because most other things are generally within acceptable tolerances (HDDs are always a bottleneck, but they're fairly similar in speed; RAM is generally *enough*, especially when dealing with gaming; etc.). The most common mismatch is the CPU : GPU. So while, yes, the CPU bottlenecks the whole system, it in fact DOES bottleneck the GPU in that, and being as the GPU has the most flexibility and significance of performance, we generally use a much more useful term and say it bottlenecks the GPU.

    Would you rather us always say, "Your CPU is bottlenecking your system" and have every noob be completely lost and less informed than when they asked the original question?
  13. nitros85 said:
    These specifics are important to understanding how hardware and mechanics work. It is in the broad scope of things that we can better understand the more precise details of what goes on, providing for more education in all things related.

    So is this the entire reason people are so argumentative? The way it comes off in my posts is saying "Bottlenecking doesn't exist!" because they do not understand what I'm saying is "The semantics are IMPORTANT, so get it right!"


    This is one of those instances that we need to "dumb things down" so more people could understand. Probably if you ask here at Tom's somebody could pinpoint the most probable point of a bottleneck (cpu, ram, hard disk, controllers, etc), but in most cases the easiest thing to point out is the cpu.

    This is like taking your car to the garage and asking an "expert at the field" a.k.a. the mechanic. If you don't know much about cars (and don't care), and the mechanic tells you that you need to change the engine to go faster, that is usually the end of that. Would you really want to know the knitty-gritty of it if you're not much interested in the repair and maintenance of cars?
  14. I don't get it. Why do you care?

    If your average Joe cared about this, then they would research this themselves and would not come here to ask.

    People don't come here to get detailed info on how a computer works, they come to get simple, straightforward advice on how to fix their problems and improve their performance. Don't confuse them.
  15. There's some good points that the people who come here want simple answers and don't really care about learning.

    If that's the case, then okay. Can't really debate that if the people who come here are the type of people who don't want to become educated.

    The reason I care though is because you have thousands of people who believe that the CPU directly bottlenecks the GPU, causing poor performance because the GPU can't work fast enough. The real reason is because the CPU bottlenecks, causing poor performance because the CPU can't work fast enough.

    In the end, the result is irrelevant because the person upgrades the CPU. But education IS important, and having ppl run around like morons thinking the reason their games are slow is bc their GPU isn't working fast enough is misleading.

    Even if it's unlikely a company will release a GPU that says "It has its own CPU so this GPU will never get bottlenecked!" it's certainly possible (We see sound cards with over loads of ram as a sellingpoint, Killer NiC network cards that boast huge performance boosts for networking, etc.) so if a feature is ever listed in the GPU mentioning "technology" that reduces CPU:GPU bottleneck, the person will be fooled and trick. Such is the case of ignorance, and why Education is always important even when it doesn't "Matter" right now.

    Because of this simple fact:

    If GPU was released with its own technology to have its own CPU into the motherboard to do all calculations, and the GPU could run without the CPU, it would do NOTHING because the CPU would still be lagging the system being the bottleneck.

    Why? Because CPU doesn't bottleneck the GPU. The CPU bottlenecks itself.

    Education leads to just one more reason to ignore worthless "features" that companies boast (lie) about to get you to buy their product. In fact, if everyone was very highly educated in a component, the companies would be forced to scratch all worthless claims and start inventing some REAL reasons to choose them over competition.

    Education is always a good thing. Misleading statements are bad.
  16. MiamiU said:
    The only immature person here is you Nitros85... how many threads will it take for you to let this syntax argument go? Are you really so needy for attention?
    So what if not everyone wants to explain things exactly like you? You just make yourself look like an arrogant asshole making a big deal out of nothing. Like others have said, learn what bottleneck means.


    Troll Fail. Go troll somewhere else please.

    K thx bai
  17. Your basic lack of social skills is the bottleneck to anyone actually caring what you have to say.
  18. Quote
    "It's certainly possible the CPU is overloaded by the game software and thus cannot feed the GPU enough information for it to process completely. In fact, this is very likely because the CPU is busy doing its own calculations while the GPU yawns, waiting to be used in the freeze-ups and lag-fest of entering a contested area."

    If that's not a GPU bottleneck caused by the CPU then what is ? I don't give a fig what the cause is. Your still arguing in reverse i would have posted on your last thread but it was locked.
    Whats actually happening is the Game is bottle necking the CPU not the CPU bottle necking the Game. I think this is what you meant with your last thread, essentially poorly coded software is causing systems to run slowly and if the Dev's could be arsed to code it properly in the first place we would get more performance from our systems and games would play better on lower spec-ed machines. Is that an accurate assesment of what you are saying ?
    Regardless of whats causing it a slow running CPU (hardware) will slow the potential speed of a GPU (hardware). If you tried running a P4 with a 5870 then that would be a clear case of the actual hardware just not being capable of keeping up. I think you are talking about situations where its a 6600 or something like that that is being talked about as bottlenecking a GPU.

    Mactronix
  19. Best answer
    nitros85 said:
    Education leads to just one more reason to ignore worthless "features" that companies boast (lie) about to get you to buy their product. In fact, if everyone was very highly educated in a component, the companies would be forced to scratch all worthless claims and start inventing some REAL reasons to choose them over competition.

    Unfortunately you can't fix stupid. So educating the whole world wouldn't improve the situation much :sol:
  20. randomizer said:
    Unfortunately you can't fix stupid. So educating the whole world wouldn't improve the situation much :sol:


    Sooo what your saying is:

    1. The world is bottlenecking stupid people.

    2. We should get a new world.

    3. We can't fix stupid people because they have nothing to lose.

    4. The world does lose calculations that stupid people need to perform better.


    See what I did there?
  21. Yes I was bored and it was worth the necro.
  22. I get it but don't get it.

    BF3 - gtx760 paired with
    fx6300: 60fps (for example) vs 4670k 75fps.

    if the 760's max load is 60% with the fx6300, will the gpu be able to utilize the remaining 40% by getting a faster cpu, or is the increase in fps solely because of the cpu?
  23. derpyy said:
    I get it but don't get it.

    BF3 - gtx760 paired with
    fx6300: 60fps (for example) vs 4670k 75fps.

    if the 760's max load is 60% with the fx6300, will the gpu be able to utilize the remaining 40% by getting a faster cpu, or is the increase in fps solely because of the cpu?


    It's because of the CPU. The faster CPU is less of a bottleneck with that video card.

    In general, the higher your MHz on the CPU the less bottlenecking occurs on the CPU... Video cards now are much faster than the processors that run the software. So by increasing the speed of the CPU you increase the interaction of the CPU and software which allows the GPU's to process information at a faster rate, thus alleviating the bottleneck issue to some degree if not eliminating it entirely.

    Think of it like a car engine: Everyone knows a stock 8 cylinder has more up front power than any 6 cylinder, but throw a supercharger on that 6 cylinder and that gap is less, if not eliminated.

    The video card needs an 8 cylinder engine to run most optimally as opposed to a supercharged 6 cylinder. Now that's not to say in some cases even that 8 cylinder isn't sufficient, and also needs to be supercharged. The analogy of high end CPU's and car engines specifically related to V8's. If a 350 5.7L V8 isn't strong enough, you need a 6.0L 427 V8 to optimize that video card. Otherwise just throw a supercharger on that 350.

    Note: Term Supercharged: Think "Overclocking"
  24. @derpyy No. The 760 will stay at 60% no matter what. The game's fps may rise with a better CPU, if the CPU is the bottleneck of that game.

    @FlukeLSX This is the opposite of what I was talking about.

    The GPU is not limited by the CPU sending it data. The GPU renders perfectly fine on its own. The GAME determines which component bottlenecks. If the Game is CPU intensive like those mentioned in the OP, then upgrading your processor will fix the problem - because the SOFTWARE is demanding calculations from your CPU. It is NOT because your GPU can't get enough information from the CPU.

    If your CPU is the bottleneck for a game like EQ2, SupCom, etc. and your GPU is only rendering at 60% utilization, then increase your CPU will NOT increase your GPU utilization. It will only increase your fps by supplying the software with more calculations (irrelevant of the GPU). If your GPU is the bottleneck, it is because it cannot render enough frames fast enough.

    I guess I did not know enough at the time to properly explain this. CPU bottlenecks don't exist when you're discussing multiple computer parts. CPU bottlenecks only exist, by themselves, in the context of the Software's demand for CPU cycles. The GPU will not improve by upgrading your CPU, because the GPU is not limited by any CPU. The software is limited by EITHER the GPU or CPU. To imply that the GPU could render more frames if the CPU was not bogged down by the software's demand for CPU cycles (nothing to do with GPU) is simply false. The GPU wouldn't render more frames because the GPU is going to be stuck at the exact utilization it was before. The CPU will not empower the GPU to render more frames. That is nonsense. Thus the "CPU is bottlenecking your GPU" is utter nonsense. A myth.

    If anyone has any actual evidence to prove this to be false, I'm all ears. However I have never seen a GPU limited by a CPU. I have only seen video games which have a high demand on the CPU, resulting in lower frames simply because the software requires CPU cycles. If there was no GPU involved, or the GPU had a feature which allowed it to be separate from the CPU (my posts where the GPU has an embedded CPU in it, bypassing the normal CPU) nothing would change because the software cannot render additional frames until it has processed what it needs to with the CPU. Not because it can't feed the GPU fast enough, but because the software renders frames independently from the GPU because the CPU is still required to process data outside of rendering graphics.
  25. derpyy said:
    I get it but don't get it.

    BF3 - gtx760 paired with
    fx6300: 60fps (for example) vs 4670k 75fps.

    if the 760's max load is 60% with the fx6300, will the gpu be able to utilize the remaining 40% by getting a faster cpu, or is the increase in fps solely because of the cpu?


    The increase in fps will solely be because of the cpu. You will not have a gpu utilize the remaining 40%, because if your bottleneck in a game is the CPU, then it is because the software requires CPU cycles. This is irrelevant of the GPU, which just renders graphics.

    It is why in a game like SWTOR, you can turn off the UI & get a huge 10-20 boost in fps. The GPU doesn't have anything to do with the UI.

    If you added a faster GPU to a very slow CPU, you would see gains in fps because the GPU is faster. Because the CPU does NOT bottleneck the GPU. Not at all. Your framerate would still suck because the software is demanding on the CPU, but a better GPU would increase fps because it would be faster than the older GPU with the same slow CPU. The better GPU would not be just as bad as the slower GPU, because the CPU "bottlenecks" it. Not at all. The CPU does its calculations, and then it gives the remaining time to the GPU to do work. If that remaining time is X, then you can explain it as Slow-Gpu give 30X while Fast-Gpu gives 300X. This will result in higher fps with a faster GPU, even though the CPU is too slow. You will get a raise in FPS upgrading hardware based on how much time the CPU has to give to the GPU. If that time is forever low, then you will see marginal improvements even when upgrading. (If Fast GPU is 2x the speed of Slow GPU, then upgrading with a slow CPU could result in going from 1 frame to 1.1 frames. Obviously that is an issue that a faster CPU could address.)


    As Melcar better explains,

    Quote:
    "Bottleneck" is such an inappropriate term, but it's now become a catch phrase. A GPU always will perform at its fullest, no matter what it's paired with. The reason someone with a 3GHz X2 has lower frames in a game (or a benchmark) compared to someone else with a 3GHz C2D (both with the same GPU) is simply because one CPU is faster than the other. Benchmarks like 3DMark show this clearly; benching the above CPUs will give you drastically different scores, but if you notice, the GPU scores would be almost the same, while the biggest difference (and what determines the final score) will be the CPU score. People say 3DMark is too CPU dependent, but that is what basically happens when you stick a faster CPU in a system... the score (gaming performance) increases.
    You need both components to game, a fast CPU and a fast GPU. Of course you got variables, like gaming at high resolutions depending more on the GPU, and so forth. However, the fact of the matter is that a slow CPU does not slow down a GPU, but rather a slow CPU slows down your overall perfomance, much like less or slower RAM or a slow HDD, would decrease your overall performance.
    So do not bother breaking your head trying to figure out if a new card you're planning on purchasing will be "bottlenecked" by your older CPU. Just get the fastest card you can afford.


    http://www.overclock.net/t/332428/exactly-how-does-a-cpu-bottleneck-a-gpu/10#post_3871447
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