To some dismay, there still is no GPU thermal monitoring support or ATI OverDrive for Linux. That could, however, change as AMD reaches a feature parity between the Windows and Linux drivers. For now, Linux users are unable to manually overclock the Radeon HD 4800 series.
Likewise, for now, if you are interested in video playback with the Radeon HD 4800 series on Linux the main option is just to use X-Video. There is no UVD2 (Unified Video Decoder 2) support on Linux at this time. When playing the Blender-created "Big Buck Bunny" 1080p H.264 movie at 1920 x 1200 with X-Video using mplayer, the CPU load between the two processing cores was 10~20%. The processor used was an Intel Core 2 Duo E8400 overclocked to 4.00GHz.
Along with the Intel Core 2 Duo E8400 clocked at 4.00GHz, the test system was made up of an ASUS P5E3 Premium (Intel X38) motherboard, 2GB of OCZ DDR3-1333 memory, and SilverStone Zeus ST75ZF 750W power supply. The graphics cards that had ran along side the Radeon HD 4850 512MB were the NVIDIA GeForce 8800GT 256MB, NVIDIA GeForce 9800GTX 512MB, and ATI Radeon HD 3870 512MB. All graphics cards were ran with their stock speeds and settings. On the software side was Ubuntu 8.04 LTS with the Linux 2.6.24 kernel and X Server 1.4.1 pre-release. The 32-bit version of Ubuntu Linux was used due to an issue with the NVIDIA Linux 64-bit driver. The drivers used during testing were NVIDIA 173.14.09 and ATI Catalyst 8.6.
The Linux graphics benchmarks used were from Phoronix Test Suite 1.0.1 with the pcqs-desktop-graphics suite. These tests include Nexuiz, OpenArena, Doom 3, Quake 4, Enemy Territory: Quake Wars, X-Plane, and GtkPerf. On the following pages are the much-anticipated Linux results for the brand-new ATI Radeon HD 4850 on Linux.