How do I determine the bandwidth my CPU is capable of pushing to my graphics card?

[TheDarkKnight]

Okay,
Here's what I am trying to figure out.

I got a really good deal on an old XFX 9800GT videocard. This baby is capable of processing over 50GB/sec of data. What I wanna be able to determine is how much of that potential can be used by my CPU. I am thinking of pairing this card up with an old AMD triple-core CPU which I am sure won't be able to saturate the videocards bandwidth by any stretch of the imagination. But since I damn sure the on-board chipset is nowhere near as fast as this videocard I wonder if I would see a performance gain or not. How would I methodically go about figuring this stuff out? Software programs or test I can do? Or even taking the specs of the CPU and computing it's "potential" pixel pushing power? Thanks.

 

[stahlhart]

Sandra will measure video memory bandwidth. Not sure how accurate or useful it is, though.

 

[bystander36]

For the most part, your CPU determines the max FPS your system can handle if there is no GPU bottleneck. Your resolution and setting choices determine how much GPU you need, taking into account the max FPS you can achieve as a result of your CPU.

So, what resolution are you using/plan to use, and what sort of settings do you want to use?

 

[TheDarkKnight]

For the most part, your CPU determines the max FPS your system can handle if there is no GPU bottleneck. Your resolution and setting choices determine how much GPU you need, taking into account the max FPS you can achieve as a result of your CPU.

So, what resolution are you using/plan to use, and what sort of settings do you want to use?

Well, the desktop resolution of the monitor would be 1920x1080 but I am not sure many video games run at that resolution, so probably 1280x1024. Maybe 1600x1200. But isn't there a simple formula so I can compute all this myself? If I go with this setup the CPU will definitely be the bottleneck.

 

[TheDarkKnight]

Sandra will measure video memory bandwidth. Not sure how accurate or useful it is, though.

I know my videocards bandwidth. It's 57.6GB/sec. I need to know how much data my CPU can feed this hungry beast per second. So I can see whether the on-board is able to consume it all. If the on-board graphics chipset can be saturated by the CPU then I will install the videocard. If the CPU can't even saturate the on-board graphics chipset, theres no reason for me to install this 256-bit beast.

 

[dguy6789]

The relation between video card memory bandwidth and CPU performance doesn't work anything like you think it does.

 

[TheDarkKnight]

The relation between video card memory bandwidth and CPU performance doesn't work anything like you think it does.

I am no expert on this issue. But this isn't exactly my first day on the block either. I think it works at least "somewhat" like I think it does. And as I've stated it here, I think its generally accurate. If I am way off base please feel free to jump in and correct the flaws in my thinking.

I believe the CPU and GPU have a very interdependent relationship on each other but I could be wrong.

 

[thilanliyan]

A 9800GT is a fairly old card. You should be fine with an AMD triple core, especially if you overclock it a bit. What model is the CPU?

 

[bystander36]

I am no expert on this issue. But this isn't exactly my first day on the block either. I think it works at least "somewhat" like I think it does. And as I've stated it here, I think its generally accurate. If I am way off base please feel free to jump in and correct the flaws in my thinking.

I believe the CPU and GPU have a very interdependent relationship on each other but I could be wrong.

For the most part, the CPU preps frames, and pretty much no matter how high your settings are, it performs its tasks at the same speed, with a few exceptions. So you can take a game now, and drop it to the lowest settings to see what the max FPS you can achieve.

The GPU takes the data given to it by the CPU and builds an image and sends it to the monitor. Your max FPS will be limited by what it can do, or the CPU limit of how fast it can prep for the frames.

The resolution you can handle with your CPU is completely dependent on what your GPU can handle. The CPU doesn't care what your resolution is.


So figure the max FPS your CPU can handle, and get a video card capable of hitting those FPS at the settings and resolution you use. That would be balanced.

 

[TheDarkKnight]

A 9800GT is a fairly old card. You should be fine with an AMD triple core, especially if you overclock it a bit. What model is the CPU?

Phenom 8450 @ 2.1GHz

 

[thilanliyan]

Try to get that CPU into the 2.6-3GHz range if you can and your cooling allows it. Is that possible for you?

 

[frozentundra123456]

Until a few months ago I was running a 9800GT with an E4500. They were pretty well matched I think. I was only running at 900p. I dont think you will do well with a 9800GT at 1080p.

A few games I felt were cpu limited, eg. Skyrim, but mostly I think I was mostly gpu limited. I did not try to upgrade the gpu though, because I think any more powerful card would have run into cpu limitations. So I think you should have a fairly matched system, albeit one that will struggle with current AAA titles, but should handle most games at reduced settings/resolution.