Hardware Pipe question

[Joseph19]

When reading the hardware specs, I found a description of the amount of parallel pipes...what is the difference between:
4x2 and
8x1
number of pipes?
Or, where can I read about it?

--Joseph

[jwatte]

An 8x1 card can do 8 pixels in parallel, each with a single texture. If you use two textures, it has to loop the pixels, so it'll do 8 pixels with 2 textures in 2 cycles.

A 4x2 card can do 4 pixels with two textures in parallel -- or 4 pixels with one texture. Thus, if you use single-texturing, that card is half the speed (per clock) of the 8x1 card.

Of course, there's many other things that affect the performance of a graphics card, just like there are 4 cylinder cars that can outrun 8 cylinder cars...

[Joseph19]

Ah, thanks! That makes sense.

--Joseph