The Radeon HD 4670 brings many of the core improvements introduced with the Radeon HD 4800 (RV770) series to the mainstream consumer at a much lower price point of under $100 USD. Even in Nexuiz there is a noticeable difference in performance when comparing the Radeon HD 4670 to the Radeon HD 4850 and with the Doom 3 and Quake 4 tests as well. However, at the same time the Radeon HD 4670 is a dramatic step up from the earlier RV635PRO-based Radeon HD 3650.
Aside from the Unigine tests, the Radeon HD 4670 is playable in the available OpenGL games on Linux. It's no surprise though that Unigine Sanctuary and Tropics drops this graphics card to its knees considering its advanced OpenGL features and it being able to strain even the RV770 graphics cards.
Overclocking the Sapphire HD 4670 had led to a minor boost in performance, but the limiting factor here was Sapphire Technology. The OverDrive limits are defined by the AIB partner inside the video BIOS. With the Sapphire Radeon HD 4670 they chose to put the upper threshold at 778MHz for the RV730XT and 1140MHz for the memory. Certainly we would like to see these values increased.
When it comes to video playback on the Radeon HD 4670, right now Linux users are bound to using X-Video. However, as we have shared earlier, UVD2 support is coming to Linux along with X-Video Motion Compensation support. With the low noise output from the Radeon HD 4670, this may make it an ideal candidate for a Home Theater PC.
The Sapphire Radeon HD 4670 512MB is currently selling for about $80 USD, which makes it an exceptional value. Though if your only concern is the frame-rate performance, for just about $40 USD more you can get slightly more out of the NVIDIA GeForce 9600GT, as is shown by our Linux benchmarks. Alternatively, you could band two (or a total of four, if using Windows) of these graphics cards together using CrossFire/CrossFireX.
If open-source support is a concern for you, right now the RV730XT does have open-source support but it's only for mode-setting in both the xf86-video-ati and xf86-video-radeonhd drivers. In the near future though there should be open-source 3D support for these newer ATI GPUs.
The Sapphire Radeon HD 4670 provides quite a bit at a great value. That combined with the Linux and open-source support from Advanced Micro Devices makes this card a worthy buy for the mainstream consumer.
Pricing information and reviews on ATI graphics cards can be found at TestFreaks.com.