ATI Mobility Radeon HD 4870
The ATI Mobilty Radeon HD 4870 from AMD is a high-end DirectX 10.1 notebook graphics card. Technically, it is based on the desktop HD 4850 and 4870 GPUs but with a lower clock rate to save energy. The HD 4870 is also equipped with GDDR5 RAM, similar to its desktop variations. The successor of the HD 4870 is the Mobility Radeon HD 5870 which supports DirectX 11.
The gaming performance of the ATI Mobility Radeon HD 4870 should be comparable to, but still a bit below, the desktop HD 4850. The high amount of shaders and the 256 bit bus allows the Mobility HD 4870 to run every DirectX 9 game in high resolutions and detail settings. Demanding DirectX 10 games, such as Crysis, can be played fluently with medium to high details. Compared to the GeForce GTX 280M, the Mobility HD 4870 delivers a similar level of performance in games.
The Mobility HD 4870 is based on the RV770 chip and features 800 stream processors (160 5-dimensional shader cores). These cores do the graphics work that would normally be done by the shader- and pixel pipelines of older GPUs. The stream processors are also called ALUs and are grouped in five-way VLIW units. Each of the five instructions of a VLIW bundle has to be independent from the others and therefore much of the performance of the HD 4870 depends on the optimization of the driver.
The Mobility Radeon HD 4870 includes Avivo HD, UVD2 and an onboard soundchip for 7.1 sound output over HDMI or DisplayPort. The UVD2 supports full bitstream decoding of H.264/MPEG-4 AVC and VC-1 streams. In addition to this, it also supports dual video stream decoding and Picture-in Picture mode for full compliancy of the current BD-Live standard. Simply put, the Avivo HD technology handles all video tasks and enables the GPU to decode HD videos.
AMD has published a current consumption of about 65 Watt for the Mobility HD 4870. Still, it is unclear if this value represents the chip alone or the entire MXM board including the memory (which we estimate would contribute about 5 Watts).
Compared to the desktop ATI Radeon HD 4870, the mobile 4870 features a slower core clock and should therefore perform more similarly to the desktop HD 4850 and 4830.
|Mobility Radeon HD 4000 Series|
|Pipelines||800 - unified|
|Core Speed *||550 MHz|
|Memory Speed *||888 MHz|
|Memory Bus Width||256 Bit|
|Max. Amount of Memory||1024 MB|
|DirectX||DirectX 10.1, Shader 4.1|
OpenGL 2.0, PCI-E 2.0 x16, Powerplay, DisplayPort support up to 2560x1600, HDMI support up to 1920x1080 (both with 7.1 AC3 Audio), 1x Dual-Link/Single-Link DVI, 1x Single-Link DVI Support (all display ports have to be supported by the laptop manufacturer)
|Date of Announcement||09.01.2009|
|Link to Manufacturer Page||http://ati.amd.com/products/mobilityrade...|