How to calculate ROP's output rate?

[Kaotik]

I know I just saw this somewhere - but how do you exactly count the output rate ROPs can do?

As example, how high resolution could X1800XL (500MHz, 16 ROP's if I remember right) go while still maintaining 60FPS, if you exclude all the other possible bottlenecks but ROP's?

 

[AlNom]

16 ROPs at 500Mhz will give a theoretical maximum of 8GP/s. So, at 60frames per second, that's 133Million pixels per frame. With 4:3, that gives a very high resolution frame, but is ultimately meaningless since there are a number of factors precluding a sustained 60fps such as overdraw, memory bandwidth, and shader power.

 

[Kaotik]

16 ROPs at 500Mhz will give a theoretical maximum of 8GP/s. So, at 60frames per second, that's 133Million pixels per frame. With 4:3, that gives a very high resolution frame, but is ultimately meaningless since there are a number of factors precluding a sustained 60fps such as overdraw, memory bandwidth, and shader power.

I know it's pointless, just going for the theoretic part here.

 

[JF_Aidan_Pryde]

Following on, you simply calculate how you want to spend 8 Gigapixels with an intended resolution and estimated depth complexity:

So at 1600 x 1200 x 2.5 depth gives you 4.8MPixels per frame.
Dividing 8GP/s by that number of pixels yields you 1666 FPS.

That number is assuming zero shader work and infinite bandwidth.