The Power of 96 Pixel Shader Processors

Everybody was amazed with 16 pixel processors of the GeForce 6800 Ultra  and the Radeon X800 XT a little bit less than two years ago: performance increases the new chips brought were just in time to enable smooth speed in the new breed of major titles: Far Cry, Doom III and Half-Life 2.

The new Radeon X1900-series has delivered an astonishing raise of the number of pixel shader processors: the new chips feature 48 of them. A question that has been discussed in our Radeon X1900 XTX review was whether we really need 48 pixel shader processors amid only 16 texture units. Even in synthetic benchmarks, for example, in pixel shader 2.0 test from the 3DMark03 the speed of the Radeon X1900 is limited by the speed of texture fetches; performance of Serious Sam 2 game was also limited by the same factor.

While the Radeon X1900-series does have some future-proof because of its astonishing arithmetic power, some titles that the gamers play today do not take much advantage of the newcomer. Those, who acquire a pair of the Radeon X1900 family products, should understand clearly that in some games performance increases over the previous generation CrossFire will not be high due to limitations in texture fetch performance, however, in games that utilize math1ematically intensive pixel shaders the new duo should offer much higher scaling.

There were quite some games where the Radeon X1900 XTX did not offer significantly improved performance over the predecessor – the Radeon X1800 XT. In those cases, the difference between the Radeon X1800 XT CrossFire and the Radeon X1900 XT CrossFire will be evem smaller. Moreover, when acquiring the Radeon X1900 XT CrossFire system you should make sure you have a processor fast enough to avoid limitations in performance in CPU-bound cases (future games will demand a rapid microprocessor anyway).

So, what should you generally expect from the Radeon X1900 XT CrossFire, keeping in mind that there is virtually one tangible improvement over the Radeon X1800 XT the new Radeon X1900 XT has: increased amount of pixel shader processors? We believe that the following:

• Do not expect substantial performance gains in games that are bound to texturing.
• Do not expect any visible speed improvements in cases when there was a memory bandwidth limitation.
• Do not expect performance increases from games that are CPU-bound.
• Do anticipate performance increments in cases where arithmetic pixel shader performance matters.

A funny thing about 96 – or nearly 100, an unbelievable number a couple of years ago – pixel shader processors is that it took ATI two graphics chips to assemble such an array, whereas Nvidia Corp. will use “96 pixel processors” moniker to boost up interest to 4-way SLI systems coming out this spring.