Product: AMD Radeon HD 6450
Company: AMD
Authour: James Prior
Editor: Charles Oliver
Date: April 7th, 2011
Architecture & Features

Radeon
Radeon
The Caicos core features 160 stream cores using VLIW 5 designed thread processors, to make 2 SIMDs (each with 80 stream cores). The architecture is derived from the Barts core, which debuted with the AMD Radeon HD 6800 series, and found in the recently released Radeon HD 6790. This means the improved graphics engine, stream cores, and render back ends are featured, providing the updated 7th Gen tessellation unit, faster backface cull and improved Anisotropic Filtering hardware. The increase in SIMDs, doubled from the HD 5450's Cedar chip, is accompanied by a doubling of color Render Output Processors to 8. The memory interface remains 64-bit but gains support for GDDR5 and the other Barts improvements. Additionally the core clock speed is up, now topping out at 750MHz vs. 650MHz in Cedar.


Caicos Architecture
Caicos Architecture

Power numbers for Caicos are very close to Cedar, specifying 20W typical board power for DDR3 equipped models and 27W for GDDR5 models, and a 9W idle. By contrast, the DDR3 equipped ATI Radeon HD 5450 was specified as 7W idle and 19W load. The good news is that means the extra 80 stream cores, even clocked 100MHz faster, only appear to need 1 more Watt of power at load. The bad news is, the tasty high bandwidth GDDR5 can increase power consumption by 40%. How much of an issue this is depends on the usage case, and is nearly entirely mitigated by the fact that there will be DDR3 equipped versions on sale, too (likely at the cheaper end of the given $55-60 price range).

Universal Video Decode Hardware
Universal Video Decode Hardware

Courtesy of the UVD 3 fixed function hardware and being suitably equipped with a HDMI 1.4a output, Caicos supports Blu-ray 3D movie playback with the appropriate software and 3D HDTV. AMD HD3D gaming is also supported with appropriate middleware driver from IZ3D or DDD, with AMD again claiming low settings on a 720p Half-HD TV being playable. Lacking the appropriate equipment we were unable to verify their claims, but Blu-ray 3D doesn't need much horsepower with the UVD 3 hardware handling the multi-view codec decoding, and Stereo 3D gaming at 720p with 30fps per eye and low settings doesn't sound unobtainable.

AMD Radeon HD 6450
AMD Radeon HD 6450

The use case for the Caicos boards is as an upgrade path from integrated graphics, be it on-CPU package as found in the Core i-series, or chipset integrated like AMD's own HD 3300/4200 series. AMD's positioning here is to provide support for newer standards such as DirectX 11 and provide more power for performance in graphics and GPU compute tasks, and power savings by offloading CPU functions to GPU.


To test performance and features we used some simple benchmarks to show the differences between three GPUs. We used our ASUS M4A89GTD PRO/USB3 mainboard featuring the AMD 890GX chipset, which includes an ATI Radeon HD 4290 integrated GPU. In comparison, we fired up the HD 6450 and the HD 5450 to show how these GPUs differ.


In operation the HD 6450 has three PowerPlay™ clock states, low, medium and high. Idle and windows 7 aero desktop is run using the low state, which runs the GPU at 100MHz engine clock and 150MHz memory clock. When UVD is in operation, or in multi-display configuration, the medium clocks of 400e/900m are used. In 3D mode or for AMD APP utilization, the high state clocks of 750e/900m are used. For cards configured with DDR3 or lower code clocks, the medium setting may not be present and the low state memory clock closer to 300MHz.

ATI Radeon HD 5450
ATI Radeon HD 5450
ATI Radeon HD 4290
ATI Radeon HD 4290

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