We were able to overclock the NVIDIA GeForce GT 220 under Linux using CoolBits. When overclocking this graphics card, the auto-detect setting was able to find the "optimal 3D clocks" at 665MHz for the GT216 core and 480MHz for the DDR2 video memory. This is a boost of 40MHz over the reference spec for the core and an impressive 160MHz on the video memory. Our overclocked results are shared with all of these test results too.
For comparing the performance of this budget NVIDIA graphics card we had compared the Ubuntu Linux performance to that of the Sapphire Radeon HD 4550 512MB clocked at 600/800Mz, Sapphire Radeon HD 4650 512MB clocked at 650/900MHz, and a Sapphire Radeon HD 4670 512MB clocked at 750/1100MHz were the graphics cards on the ATI Radeon side. The other NVIDIA graphics cards tested included an ASUS GeForce 8400GS 512MB clocked at 500/333MHz, Gigabyte GeForce 8500GT 512MB clocked at 500/400MHz, a Gigabyte GeForce 8600GTS 256MB clocked at 675/1008MHz, and a Sparkle GeForce 9500GT 1GB clocked at 550/400MHz. With the XFX GeForce GT 220 1GB we ran it at its stock frequency of 625/400MHz and then again when it was overclocked at 665/480MHz. While the NVIDIA graphics cards were using the NVIDIA 190.36 beta driver, on the ATI side was the Juniper press driver that is fglrx 8.67.4 / OpenGL 2.1.9115.
The tests we used for comparing this collection of PCI Express graphics cards were MPlayer 1080p H.264 video playback, Nexuiz, Warsow, World of Padman, Lightsmark, GtkPerf, and QGears2. All of these tests were ran under the Phoronix Test Suite using the latest v2.2 Bardu snapshot.