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Spot the system bottleneck (with proof)

Last response: in Systems
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July 23, 2009 3:14:26 PM

Hi all! I have been looking all over the web for the answer to the question how to find a system's bottleneck but i haven't found any convincing answers so far.. And i dont mean saying it's the HD or the RAM just by experience or common sence but answers based on precise numbers from tools or measurments..
One tool i have found is windows' perfmon.msc but in many cases it doesn't provide a clear answer to the question.

To be a little more specific, my rig is

i7 920
Gb EX58-UD4
OCZ3P1333LV3GK 3GB (3X1GB) DDR3 PC3-10666 CL7
Ati Sapphire HD4870
Seagate 7200.12 ST3500410AS

Let's assume i am unzipping a file
No component causes an "obvious" bottleneck exept from the Hard disk but how can this be justified with numbers?
Besides, in a much older rig with crappy parts the answer might not be so obvious..

Thanks in advance for your replies!!
a b B Homebuilt system
July 23, 2009 3:22:11 PM

Unless you have similar components to switch out for each one its not possible to identify bottlenecks with components other than the CPU. If you overclock the CPU and a certain task speed up it was limited by the CPU, in order to identify a bottleneck with the hard drive you would have to try swapping in a faster hard drive to see if it improves performances, same with the ram and the video card.
July 23, 2009 8:11:55 PM

The only thing that comes to my mind is your hard drive, its kinda low end if we take into consideration all the other parts you have...

But since I dont fully understand what you are asking here I might be wrong.... So you unzip a file and WHAT exactly happens?
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July 24, 2009 12:31:04 AM

Nothing special really, unzipping was just an example of a common task :) 
You said it is the Hard Drive, but can you prove it with evidence?
What i'm asking is a little difficult to say so i'll give you an example. Forget my i7 rig, suppose my system was much older, like a Pentium4, an old mobo and DDR1 400 Ram and i had a brand new superfast SSD hard drive, so the HD would not the slowest component. How would i find the bottleneck then? With what evidence?

If what Hunter315 said is true, there's not really a way to tell what the bottleneck is (without trying on other components) but i find that hard to believe, there must be a way, a software or something!
a c 122 B Homebuilt system
July 25, 2009 4:56:33 PM

You are not using the term "bottleneck" correctly.

In your example of unzipping a file and writing it to disk, a faster CPU will unzip the file more quickly. A faster disk system will save it more quickly. There is no bottleneck.

A bottleneck (sloppy and imprecise term that it is) occurs when one component limits the performance of another. In the unzipping example, the performance of the CPU does not limit the performance of the disk. The performance of the disk may depend on the CPU, but that is not the same thing.

The usual bottleneck that we are concerned with is the CPU-GPU. If you team an old, slow CPU with a fast GPU, the frame rates will be limited because the CPU just cannot keep the GPU fed. If you team a fast CPU with a slow GPU, frame rates suffer because the fast CPU just cannot push the GPU faster than it is able to go.

July 25, 2009 5:53:10 PM

jsc said:
You are not using the term "bottleneck" correctly.

In your example of unzipping a file and writing it to disk, a faster CPU will unzip the file more quickly. A faster disk system will save it more quickly. There is no bottleneck.

A bottleneck (sloppy and imprecise term that it is) occurs when one component limits the performance of another. In the unzipping example, the performance of the CPU does not limit the performance of the disk. The performance of the disk may depend on the CPU, but that is not the same thing.

The usual bottleneck that we are concerned with is the CPU-GPU. If you team an old, slow CPU with a fast GPU, the frame rates will be limited because the CPU just cannot keep the GPU fed. If you team a fast CPU with a slow GPU, frame rates suffer because the fast CPU just cannot push the GPU faster than it is able to go.


+1 "jsc" [:jaydeejohn:5]
July 25, 2009 7:05:00 PM

jsc said:

A bottleneck (sloppy and imprecise term that it is) occurs when one component limits the performance of another.


Well, that depends on which side of the "bottle" you are standing ;) 

Anyway, if you give me an answer about your CPU-GPU example i will figure out the rest.

jsc said:
...If you team a fast CPU with a slow GPU...


How can you tell what is the "slow" and "fast" part (GPU or GPU)?
a b B Homebuilt system
July 25, 2009 7:33:29 PM

See here
http://www.tomshardware.com/reviews/phenom-versus-i7,23...

Left 4 dead is almost always a CPU bottle neck because it isnt very graphics intensive. In this case the way you can prove its a CPU bottle neck is that the OC'd CPU's give better frame rates, and increasing the load on the GPU's by adding AA and AF makes almost no difference in frame rates which means that you are not maxing out the GPU in this case.
July 26, 2009 12:52:16 AM

I got it now hunter, thank you :) 
So it's all about trial and error i guess..
a b B Homebuilt system
July 26, 2009 12:59:05 AM

yup, just figure out what the stuff you do most commonly relies on the most and make sure those components are quick because there is always going to be a limiting factor you just want to minimize its affect on performance.
!