Intel Extreme Graphics - The Technology
The integrated graphics engine in the 845G chipset is a much more refined version of the one found in the 815 series. Featuring Intel's Rapid Pixel and Texel Rendering (RPTR) engine architecture, the graphics core utilizes special pipelines that allow both 2D and 3D operations to overlap. It also features an 8x compression method which helps to reduce memory bandwidth usage, therefore it helps to reduce the amount of memory used to store textures. The core also supports quad texture rendering, which basically means that it can handle four textures in a single pass.
Intel also introduced its own method of rendering 3D scenes, known as Zone Rendering technology. With Zone Rendering, Intel is able to make better use of its memory bandwidth by dividing and sorting out a particular 3D scene into zones. Triangles associated with a respective zone are placed into the same zone in the memory and are then processed one at a time by the 3D graphics pipeline. The pipeline then renders one zone at a time, effectively reducing the requirements of high memory bandwidth. Since the render cache can be optimized to contain all the significant color and depth information of a particular frame, the need for memory accesses to these information from the memory is eliminated.
The lowered memory bandwidth requirements also helps to simplify the memory interface and memory technology. In this way, memory usage can be reduced and you need not allocate large memory to the graphics core for rendering complex scenes. This allows systems to be built with its main memory shared with the graphics core, thus, lowering the total cost of the system. However, since a particular frame is always rendered in one zone at a time, we don't expect to see lightning fast 3D graphics with Zone Rendering.
If you intend to use the built-in graphics in the 845G chipset, you should be prepared to allocate memory to the graphics core. In the BIOS, one can pre-allocate either 512KB, 1MB or 8MB to graphics alone. Now, 8MB sounds like a little bit too tiny for most of today's 3D games to run. But the 845G features what is known as Dynamic Video Memory Technology (DVMT). Once you are in Windows and running the Intel Extreme Graphics Driver, the driver will make a Direct AGP request for more memory when it is required to perform complex 3D scene rendering. This is really nothing new but this feature helps to reduce the amount of system memory used in the system by the graphics subsystem. In cases when you do not need the memory, the driver frees the memory to the system. This is better management of the system memory as compared to other integrated graphics chipset where once it is allocated in the BIOS, the operating system will never get to use them.
The heatsink used to cool the new 845G GMCH. Judging from the size, you can tell that the core logic actually runs hot. Not surprising since the graphics core is actually clocked at 200MHz.
The GMCH heatsink is soldered to the board. There's no way you can replace it with a new and meaner heatsink.