Memory Bandwith!!!

[MikeB]

Tyrannical said:

ssj12 said:
DDR3 @ 2000MHz with three channels is plenty.

No, it's not.

22.4GBS memory bandwidth sounds like a lot, but it's not enough to do complex graphical operations like HDR, alpha-blending, and anti-aliasing at 30/60 fps.

The 360 does most of that in the 10MB frame buffer, and it has a 256GBS of memory bandwidth between the frame buffer and GPU.

It's not like the Xenos can handle all of that, this due to tiling issues. 10 MB is not enough to fit 720p graphics with Anti-aliasing, that's why demanding 720p games run at 30 FPS instead of 60 FPS. However 640p can fit into EDRAM with anti-aliasing, so a game like Call of Duty 4 can run at 60 FPS.

HDR together with Anti-aliasing is not really an option on the 360 due to tiling issues at HD resolutions. That's why Halo 3 is only 640p and lacking Anti-aliasing, running at an unsteady 30 FPS. Bungie did not lack funds or expertise. But for example Killzone 2's lighting is far more advanced, with more effects, this at 720p with anti-aliasing and a rock solid 30 FPS (they still have a lot of technical headroom though, for a Killzone 3).