X-bit labs

ATI Radeon X1650 XT Graphics Card Review (page 2)

Category: Video

by Alexey Stepin , Yaroslav Lyssenko

[ 01/19/2007 | 11:58 AM ]

ATI RV560: Specification

Like its elder brother RV570, the RV560 chip is manufactured on TSMC’s 0.08-micron tech process but has fewer functional subunits and uses a 128-bit memory access. As a matter of fact, the RV560 and RV570 are both the same 330-million-transistor chip, but some functional units and memory controller interfaces are disabled in the former whereas the latter is a full-featured version of the basic chip.

The first thing to be noted is that the Radeon X1650 XT has two times more pixel processors than the GeForce 7600 GT, but has the same number of ROPs. It means it is going to be considerably faster than the Nvidia card at complex mathematical computations and at least equal to it when it comes to full-screen antialiasing. The Radeon is also equipped with more vertex shader processors than its opponent, which should ensure it an advantage in geometrically complex scenes such as scenes with dynamically generated vegetation.

The graphics cards are roughly equal in terms of memory bandwidth, but the difference in the memory controller architecture should be taken into account. The Radeon X1650 XT uses a ring-bus architecture with two bidirectional buses (the cut-down RV560 may be using unidirectional buses, though) whereas the GeForce 7600 GT features a classic topology. The ring-bus topology is known to ensure lower memory access latencies, so the advantage is on the Radeon X1650 XT side again. It may show up in such cases when the graphics memory performance is of paramount importance like in HDR or full-screen antialiasing modes.

Theoretically, AMD solution’s weakness may come from its fewer TMUs and subunits that process the Z-buffer, yet it’s not a fatal handicap, just as it is not for RV530-based graphics cards. It is unlikely to prevent the new product from competing successfully with the GeForce 7600 GT as we are going to see in our tests soon.

Like the RV570, the RV560 chip incorporates a full-featured Compositing Engine. You can learn more about the changes in CrossFire technology on new ATI Radeon graphics cards from our comparative review of Radeon X1950 Pro and GeForce 7900 GS.