What are ROPs, and do they matter?

[khothmod]

The question is in the title. 

[Godlygamer23]

ROPs are a big part of video cards. If you look at for example the GTX 760 vs the 660 Ti. They use the exact same architecture, but the 760 is able to achieve better performance despite having less CUDA cores due to ROPs. The main area where more CUDA cores can matter is in compute heavy scenarios.

 

As far as the function is concerned, here is a quote from a website known as GPUReview:

Raster Operators (ROPs) handle several chores near the end of the of the pixel pipeline. ROPs handle anti-aliasing, Z and color compression, and the actual writing of the pixel to the output buffer.

Recently nVidia has been reducing the number of ROPs on their graphics cards as shading power gets more and more important. For example, the 6600GT had 8 fragment pipelines, but only 4 ROPs. However, in just about any modern game, far more than 1 cycle is spent shading each pixel. Thus, cards with the same number of ROPs as fragment pipelines would end up with ROPs sitting idle waiting for input.

The move towards fewer ROPs than fragment pipelines is a way gpu designers eliminate unneeded complexity from their chips without sacrificing performance. And less complexity means higher speeds and better yields will be attainable.

http://www.gpureview.com/raster-operator-article-362.html

[khothmod]

2 minutes ago, Godlygamer23 said:

ROPs are a big part of video cards. If you look at for example the GTX 760 vs the 660 Ti. They use the exact same architecture, but the 760 is able to achieve better performance despite having less CUDA cores due to ROPs. The main area where more CUDA cores can matter is in compute heavy scenarios.

 

As far as the function is concerned, here is a quote from a website known as GPUReview:

 

 

http://www.gpureview.com/raster-operator-article-362.html

I've heard that the amount of ROPs (talk 32 vs 64) isn't too big of a bottleneck or deal breaker anymore, unless you want a card marketed towards VR... Is this true? 

[Godlygamer23]

3 minutes ago, khothmod said:

I've heard that the amount of ROPs (talk 32 vs 64) isn't too big of a bottleneck or deal breaker anymore, unless you want a card marketed towards VR... Is this true? 

It also depends on the architecture behind the GPU as that's also important. Just like the number of CPU cores do not inherently matter. If the architecture is terrible, it will likely be terrible at almost everything. So when it comes to VR, rely heavily on reviews to see what kind of performance you can expect with the same, or similar setup. I cannot give you a definite answer because as I said, the architecture is very important. Generally speaking, more ROPs means better performance per the same architecture.

[khothmod]

1 minute ago, Godlygamer23 said:

It also depends on the architecture behind the GPU as that's also important. Just like the number of CPU cores do not inherently matter. If the architecture is terrible, it will likely be terrible at almost everything. So when it comes to VR, rely heavily on reviews to see what kind of performance you can expect with the same, or similar setup. I cannot give you a definite answer because as I said, the architecture is very important. Generally speaking, more ROPs means better performance per the same architecture.

Thank you very much. That was very helpful and informative. 

[Sakkura]

13 minutes ago, Godlygamer23 said:

ROPs are a big part of video cards. If you look at for example the GTX 760 vs the 660 Ti. They use the exact same architecture, but the 760 is able to achieve better performance despite having less CUDA cores due to ROPs. The main area where more CUDA cores can matter is in compute heavy scenarios.

That may have been as much or more due to memory bandwidth. ROPs and memory bandwidth are often closely linked anyway though.

[Godlygamer23]

3 minutes ago, Sakkura said:

That may have been as much or more due to memory bandwidth. ROPs and memory bandwidth are often closely linked anyway though.

I can't disagree with that. The 760 did have additional memory bandwidth so it could've contributed to it.