ATI Radeon HD 4290 Graphics Core
Contrary to our expectations, there is nothing particularly new about the graphics core integrated into the AMD 890GX chipset. It is largely similar to the core found in the older AMD 785G. That's why the names of the cores differ so little, by the way: Radeon HD 4290 and Radeon HD 4200. There is still no DirectX 11 support as the new core only complies with the DirectX 10.1 specifications. The only thing the developer did was to increase the performance slightly so that the Radeon HD 4290 could be competitive to computers that use the integrated graphics core of Intel's LGA1156 processors.
What is the simplest way to boost performance? Increase the GPU's clock rate, of course! Therefore, the Radeon HD 4290 core in the AMD 890GX is clocked at 700 MHz whereas the Radeon HD 4200 used to be clocked at 500 MHz. Otherwise, the two cores are identical, both being based on the RV620 architecture with 40 shader processors.
The video engine, UDV2, has remained the same as in the AMD 785G. It did not actually call for improvement since its functionality is up to today's requirements. As we saw in our tests of the AMD 785G, the CPU load was very low when playing video using that graphics core. The UVD2 engine offers hardware decoding support for MPEG2, VC-1 and H.264 and can process two independent streams simultaneously. On the downside is the inability of the AMD 890GX (and 785G) to transmit TrueHD, DTS-HD or uncompressed multichannel LPCM audio via HDMI, making it less appealing for HTPC systems.
Like the Radeon HD 4200, the graphics core in the AMD 890GX chipset can use not only some of the computer's main system memory for its purposes, but also a dedicated 128-megabyte DDR3-1333 video buffer (Sideport Memory) represented by a separate memory chip. Besides using this buffer as dedicated graphics memory, the Radeon HD 4290 can also utilize it as cache to improve performance while working with system memory. It must be noted that mainboard makers did not often implement Sideport Memory technology in their AMD 785G-based products whereas most of AMD 890GX-based ones are going to be equipped with that video buffer.
We performed a series of tests to check out the 3D performance of the new chipset and compared the AMD 890GX, AMD 785G and Intel HD Graphics. For this comparison we took Intel Core i3-540 and AMD Athlon II X4 635 processors and the following mainboards: Gigabyte GA-H55M-UD2H, Gigabyte GA-MA785GT-UD3H and Gigabyte GA-890GPA-UD3H.
The tests suggest that AMD's solution works. The higher clock rate proves to be sufficient to make the AMD 890GX the fastest chipset with integrated graphics core. The Sideport Memory adds the graphics core a dedicated memory bus and helps increase 3D performance, making the Radeon HD 4290 an unchallenged leader.