CPU Bottleneck - What is it, and how it affects your games.
Decided to make this thread as there's a little bit of Bottleneck-phobia going around the Shogun II forums recently. I thought about posting this in The Basement, but it would undoubtedly get more views (and do more good) here.
What is a Bottleneck?
Originally Posted by Wikipedia
What does this mean?
In simple terms, this refers to a system not being able to optimum levels because one (or more) components are holding it back.
I like to say that CPU bottleneck is like a roof. The power of your CPU determines how high the roof is.
What is CPU Bottleneck in games and why does it happen?
In games, a CPU bottleneck refers to the how the processor holds back the graphics card(s) from rendering more frames each second. The graphics card is not fully utilised and as such, you don't get full performance from your system.
This happens because in addition to all the visual rendering done by the graphics card, there is plenty of internal processing done by the CPU corresponding to what is going on inside the game. Physics is a particularly noticeable example, which is why PhysX (Nvidia's proprietary GPU-accelerated Physics method) is such a big marketing gimmick.
Why do people say that CPU Bottleneck is bigger at low resolutions?
Because it is.
All of the calculations that the CPU needs to do remain static regardless of the resolution. This is because the internal calculation process that the CPU has to do inside a game is dependent on what goes on in the game, and not how big the screen is.
As your resolution gets larger, the GPU has to render more pixels which affects performance. Simply put the larger the resolution, the more powerful your GPU needs to be to keep equal framerates with the same settings.
That means, that as your resolution gets the larger, the less the CPU matters to bottleneck. No matter the resolution, CPU load stays the same, while GPU load increases.
So, am I affected by CPU Bottleneck?
Everyone is affected by CPU bottleneck.
The question is "how badly am I affected by CPU bottleneck?" and "does it noticeably impact on my gameplay experience?"
I previously said that CPU bottleneck is like a roof. If your CPU is powerful enough, then the roof is high enough for a good and smooth gameplay experience.
So, is CPU bottlenecking the reason of my low framerates? How do I find out?
If your CPU is based on the LGA 1155 (2nd gen. Intel Core i3/5/7), LGA 1156 (1st gen. Intel Core i3/5/7), LGA 1366 (1st gen. Intel Core i7) or on the AMD AM3 sockets (Athlon II x3/x4 and Phenom II x2/x3/x4/x6), then CPU bottleneck is unlikely to be the cause of your low framerates.
If your CPU is older or weaker than the above mentioned CPUs, then test the game at an extremely low resolution. If your framerates improve, then CPU bottleneck is not your issue. If framerates stay the same, then CPU bottleneck could be your issue.
Note that it takes an incredibly old and/or weak CPU to provide a game crippling bottleneck, and there are plenty of driver or game related issues that could be the cause of your problem. This is particularly true if you are using one of the newer processors I listed above.
I use more than one GPU, will I encounter a CPU Bottleneck?
I'm getting a little lazy, but there is a very good (if a little old) analysis that deals with exactly this.
http://benchmarkextreme.com/Articles...alysis/P1.html
Summary: You best be overclockin', son.
So how do I combat CPU Bottleneck?
Overclocking. That's an entirely different issue altogether and I don't recommend anyone doing it without reading up on it first.
But overclocking is the primary way, outside of a better CPU to reduce CPU bottleneck in games.
I have a question and/or comment.
Feel free to post them here. If I'm not too busy or lazy, I'll try and respond to each query.
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Most likely it's unoptimized demo versions fault , but if it is not than your cpu's.If full version will take advantage of quad cores than your cpu will be bottlenecking.
