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Exactly How Does a CPU Bottleneck a GPU?

post #1 of 56
5/15/08 at 8:01pm
Thread Starter 
I'm very unfamiliar with this concept which is pretty logical, but I would still like to know the requirements for bottlenecking.

I'm thinking about getting a 4870 for my current computer after I get my bank account setup.
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post #2 of 56
5/15/08 at 8:03pm
ever try putting a Pentium 4 and a 3870x2 together?, not too pretty
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post #3 of 56
5/15/08 at 8:10pm
I think something along the lines of:
The cpu cant process the info or load as quick as the GPU. Or the cpu has more room left that the GPU isnt taking advantage of.
Perhaps?
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post #4 of 56
5/15/08 at 8:11pm
My cpu bottlenecks my gpu right now. it results in game stuttering
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post #5 of 56
5/15/08 at 8:15pm
Bottlenecks can occur either way. Basically what it means is that the slowest component determines the final performance in a certain application.

In gaming, for example, the GPU is the most important part. However, if you have a high-end GPU with a low-end CPU, the CPU simply can't keep up, and the CPU is the part that determines the final performance. Other way around, when you have a high-end CPU and low-end GPU, the GPU is the bottleneck.

Now, at any kind of reasonable resolution (1680 x 1050 and up), CPU bottlenecks are rare.
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post #6 of 56
5/15/08 at 8:17pm
Thread Starter 
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.
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post #7 of 56
5/15/08 at 8:29pm
Basically:

If a CPU is taking a long time to calculate where a person is at or where they're aiming, then how is the GPU supposed to draw that to the screen? It waits for the CPU to "finish" and then draws it. As simple as that.
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post #8 of 56
5/15/08 at 8:30pm
Quote:
Originally Posted by dieanotherday View Post
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.
You can't state it like that. Too many factors involved.

A CPU can bottleneck a GPU at low resolutions, but at high resolutions the tables will be turned. That's one.

Enabling AA/AF and such put more stress on the GPU, reducing bottleneck.

etc etc.
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post #9 of 56
5/15/08 at 8:32pm
Quote:
Originally Posted by dieanotherday View Post
I want to know a ratio of speed a cpu can bottleneck a gpu.
Such as a 800mhz pentium III can handle everything up a 400 mhz gpu.
This is impossible because there is a wide range of both cpu and gpu architectures.
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post #10 of 56
5/15/08 at 8:34pm
Think of it more generally:

If your CPU is fast think of it as water being dumped into a funnel, if the funnel opening isnt big enough water will not get through, basically hindering the flow (processes)

Its vice versa for CPU bottlenecking. There isnt enough water to feed the funnel its full flow potential.
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