|
As we have somewhat glossed over the integrated graphics core thus far, let's take a closer look at it. The Extreme Graphics is Intel's first new graphics core since the i752 of 1999. Like the i740 of old, the Extreme Graphics is targeted at the low-cost market, a fact clearly illustrated by its 200MHz single rendering pipeline architecture. Being a SMA (shared memory architecture) solution, the immediate drawback is its memory bandwidth consumption. Obviously, this would negatively influence overall system performance, as the 2.1GB/s of peak bandwidth offered by DDR266 SDRAM isn't sufficient to match the 4.26GB/s of the 533MHz quad-pumped FSB, much less with the integrated graphics core sipping away bandwidth.
Realizing this, Intel has implemented several bandwidth saving measures. Among them are the graphics pipeline's ability of processing 4 textures in a single pass. There is also what Intel dubs Dynamic Video Memory Technology, an acronym for the way the graphics core allocates memory for use. As shared memory architecture implies, the graphics core has no dedicated video memory and must wall off a chunk of main system memory (and hence system memory bandwidth) for its own use. As compared to conventional methods which set aside a fixed chunk of contiguous main system memory, Intel opted to bypass the AGP GART, using its own translation tables for memory addressing. This enables the allocated memory to be non-contiguous and the allocation of memory to be truly dynamic. The GMCH will resize the amount of allocated memory according to application demands, freeing up as much system memory as possible to maximize system performance. Another bandwidth saving measure is Intel's Zone Rendering Technology. In conventional immediate mode rendering, as each polygon is sent to the graphics hardware, it immediately goes through the pipeline and is rendered into the frame buffer. Any portion of the frame buffer may be drawn at anytime during a single frame. Zone Rendering divides the frame buffer into a number of rectangular zones, rendering all the pixels within a single zone before proceeding to the next. In effect, this approach optimizes the rendering process for the GMCH's internal buffers. Since the depth/Z data is now stored within the chip's cache, depth buffer reads and writes, as well as potential frame buffer updates are eliminated, saving a significant amount of system memory bandwidth. As we have seen so far, the performance of the Extreme Graphics is in the ballpark of the GeForce2 MX200. Although not impressive by today's standards, it is more than sufficient to provide a decent gaming experience at sufficiently low resolutions and color depths. One positive way to look at it is that the Extreme Graphics should be sufficient to tide you over until say the NV30 and NV35 hit the streets later this year.
|
|||||||||||||
