Test System Specs & 3Dmark Vantage

Test System Specs
- Intel Core i7 920 (Overclocked @ 3.70GHz)
- x3 2GB G.Skill DDR3 PC3-12800 (CAS 9-9-9-24)
- Asus P6T Deluxe (Intel X58)
- OCZ GameXStream (700W)
- Seagate 500GB 7200-RPM (Serial ATA300)
- AMD Radeon HD 6870 (1GB)
- AMD Radeon HD 5970 (2GB)
- AMD Radeon HD 5870 (1GB)
- HIS Radeon HD 5850 (1GB)
- AMD Radeon HD 5830 (1GB)
- HIS Radeon HD 5770 (1GB)
- HIS Radeon HD 5750 (1GB)
- Asus GeForce GTX 580 (1.5GB)
- Inno3D GeForce GTX 480 (1.5GB)
- Palit GeForce GTX 470 (1.3GB)
- Gigabyte GeForce GTX 460 (1GB)
- Inno3D GeForce GTX 460 (768MB)
- Palit GeForce GTS 450 (1GB)
Software
- Microsoft Windows 7 Ultimate 64-bit
- Nvidia Forceware 262.99
- AMD Catalyst 10.10

According to 3Dmark Vantage, the GeForce GTX 580 is 39% faster than the GeForce GTX 480 at 2560x1600, a considerable increase in performance. That said, the same benchmark believes the Radeon HD 5870 is 4% faster than the GeForce GTX 480, so we'll take its findings with grain of salt.