The clock speeds on the 7900GT are a more modest 450/660MHz and 560/700MHz for the 7600GT. The GT is a 24 pipeline part but the 7600 has only 12 pipelines and eight ROPs.
In terms of 3D features though thereâ€™s not much thatâ€™s new. CineFX 4.0 is still employed to deliver Shader Model 3.0, along with with 2x, 4x, 8x and 8xs standard FSAA as well as transparency adaptive supersampling and transparency adaptive multisampling. Thereâ€™s also an extra quality 8x and 16x mode reserved for SLI systems.
One new feature is the addition of dual dual-link DVI outputs on the 7900 GTX and the GT. This brings NVIDIA into line with ATI, who has had dual dual-links since X1800. Dual dual-link is required for those that wish to run two 30in screenâ€™s each with a resolution of 2,560 x 1,600 off one card. (If you do this, please send me a photograph!). The 7600 has one dual-link and one single link DVI outputs.
NVIDIA has also updated its drivers (84.20 beta) to support H.264 decoding. However, as well as the drivers, this requires NVIDIAâ€™s PureVideo decoder, which you have to pay for, and a third party application from the likes of InterVideo or Cyberlink, which you also have to pay for. Once you have these youâ€™ll get silky smooth 1080p playback of H.264 content, which is a sight to behold. However, it also works for 6xxx and 7xxx series cards, so itâ€™s not necessary to buy a 7900 to get this.
ATI also had H.264 support of course, also in conjunction with a decoder from Cyberlink and the latest drivers. It also offers the AVIVO video converter, which is a really useful tool for encoding your movies for PSP and iPod video.
On then to the performance. To test we hooked up our NVIDIA test bed, which consists of an AMD FX-60 in an Asus A8N32-SLI Deluxe (nForce 4 SLI chipset) and 2GB of Corsair RAM.
Our benchmarks consisted of our recently updated suite of 3D tests. We start with 3DMark 05 and 06 before running in-house recorded timed runs of Call of Duty 2 and Counter-Strike: Source â€“ the Militia map with HDR enabled. We run Quake 4 for OpenGL testing. All tests are run three times and averaged. We hope to add more game tests as soon as possible which weâ€™ll hopefully employ on reviews of retail cards.
We ran tests of the 7900 GTX reference cards and compared with 7800 GTX 512 and the X1900 XTX. For dual card testing we compared two 7900 GTXs with two 7800 GTX 512MB and X1900 CrossFire. For our ATI testing we used the same Athlon FX-60 CPU and 2GB of memory in an Asus A8R32-MVP Deluxe motherboard based on the ATI RD580 chipset.