OC: Radeon HD2900XT 512 MB vs GeForce 8800GTS 640 MB - Testing explained
Author: Luka Rakamaric
Date: 26 Jun 2007

Since this is not a complete review, but rather a presentation of OC potential that an average user can achieve (no voltmodding or custom cooling), we also chose a resolution that most users will use with such cards, and that is 1680x1050, most commonly used on 22?? LCD displays. We also used two AA modes, 4x, and 16x, both with 16x AF.

Because outside ambient temperatures at the time of the test were around 32 degrees, we turned on our air condition and maintained a room temperature of 20 degrees to ensure comparable conditions for both cards.

The R600 in such conditions was able to reach a max stable overclock of 840 MHz (+13,5%) for the core and 1050 MHz (+21,2%) for the memory. That is a full 100 MHz more than the stock speed, which is very good considering that this is a top of the line card. The important number to remember here is the percentage, 13,5%. The test was done in a closed case and not on a testbed, to simulate real life conditions regular users will encounter in their homes.

The G80 was able to reach a maximum overclock of 648 MHZ (+29,6%) for the core and 999 MHz (+24,8%) for the memory. Since G80 in the GTS is underclocked compared to the GTX, this is somewhere around what we expected. The main thing to notice here again is the percentage of the clock increase, which is almost double to that of the R600. Because performance scales linear to the clock of the core (assuming the CPU or other components are not the bottleneck), you can see that the 8800GTS is in fact a much better overclocker than the HD2900XT, despite its higher clocks.