X-bit labs

ATI RADEON X800: R420 Totally Exposed (page 27)

Category: Video

by Tim Tscheblockov , Alexey Stepin , Anton Shilov

[ 05/04/2004 | 06:42 AM ]

It is probably the because of the fact that RADEON X800 PRO features reduced number of pixel pipelines: 12 against 16 by RADEON X800 XT (or 3 “wide” pipelines against 4, which would be more correct). That is why HyperZ HD cannot process the tiles of the same size as before efficiently, because the graphics processor cannot check the required number of Z values within the same clock cycle. Therefore the tile size is most likely to be made twice as small now, so that HyperZ HD starts looking just like HyperZ III by RADEON 9800 XT.

When we disable Z writes, the situation remains almost the same: the numbers are the same as on the previous diagram.

When we disable color writes, the graphics cards demonstrate their maximum Z writing speed: NVIDIA GeForce 6800 Ultra and GeForce FX 5950 Ultra double their performance in this mode. Unexpectedly high results obtained on NVIDIA GeForce 6800 Ultra look promising. As you remember, we have already seen this picture in our NV40 Review (the card shows higher performance than its theoretical maximum).