The nVidia GeForce 8600GTS (aka 'G84' core) is built on TSMC's 80nm manufacturing process and contains 289 million transistors. According to nVIDIA the GeForce 8600GTS core has a maximum power draw of 71W, a hair below the 75W the PCI Express x16 bus can provide. To be on the safe side the GeForce 8600GTS has a six pin PCI Express power connector so if the videocard needs more power during overclocking it gets it.

By default the nVidia GeForce 8600GTS has a default core speed of 675 MHz while the stream processors hum along at 1.45 GHz. The nVidia G84 core only comes equipped with 32 stream processors as opposed to 96/128 with the nVidia G80 core.

The memory runs at a flat 2 GHz, yet with the GeForce 8600GTS the memory bus width is only 128 bits. That alone should tell potential users that the card will be mainly memory bandwidth limited, especially so at higher resolutions or with AA enabled. Maximum memory size is 256MB for all G84 based videocards.

Gone are the hard coded Vertex and pixel shaders in the G84 core, they have been replaced with a more flexible Stream Processor (or unified shader) that calculates both types of data. The Stream Processors run at a blistering 1.45 GHz. Traditional core clock speeds as we know it are dead, as several internal processors are running at different speeds.

It's important to note that the GeForce 8600GT only has 32 stream processors while the sightly better GeForce 8800GTS model has 96 and the 8800GTX 128. If you remember, 16 stream processors equals one thread processor so there is only two in the nVidia G84 core.

Each Thread Processor has two groups of eight Stream Processors, and each group talks to an exclusive texture address filter unit as well as well as being connected to the shared L1 cache. When more memory is needed, the Thread Processor connects to the crossbar memory controller. nVIDIA's crossbar memory controller is broken up into two 64 bit chunks for a total bus width of 128 bits.

By moving the GPU towards a threaded design, the nvidia G84 is much more like a processor than any graphics core of the past. Any type of data - be it pixel, vertex, or geometry shader can be processed within the Stream Processor. This allows load balancing to occur between the various tasks.

Examining CPU Load with PureVideo

To test PureVideo's High Definition accelerating capabilities on the Biostar Sigma-Gate GeForce 8600GTS, PCSTATS will play back a video downloaded from Microsoft's WMV HD Content Showcase through Windows Media Player 10. "The Discoverers" (IMAX) video is available in both 720P and 1080P formats. AMD processor utilization will be monitored via Task Manager.

When running the 720P version of the high definition Discoverers video, CPU usage jumps between 15-18%. Not too bad and it leaves plenty of resources for background tasks.

The 1080P version of the Discoverers video uses even less CPU resources and CPU usage hovers between 13-15%. Next up are the overclocking tests you've been eagerly awaiting!