What is the 8600 GTS?

Until now known as the G84 Nvidia's 8600 is the world’s first midrange DirectX 10 graphics card. With a price point of $149 - $229 (GTS will retail for approx £150 in the UK) the card aims to make DirectX gaming accessible for as many consumers as possible. Although the core is derived from the 8800 series school of thinking there are numerous changes which have been made in order to create a product which is cheaper to make/buy however not all of these are detrimental.

The 8600 is an 80nm GPU consisting of 289 million transistors and 32 stream processors. As with the 8800 series the stream processors are capable of handling vertex, pixel, geometry and physics work through their programmable nature. The reference speed of the GTS core is 675 MHz and the shader clock is by default 1.45 GHz. Memory is of course configurable by the card makers, however the reference design features 256Mb of DDR3 clocked at 1000Mhz on a 128bit memory bus. The lower spec GT which will retail for $149 is clocked at 540 MHz core, 1.19 GHz shader and 700 MHz DDR3.

Both cards feature 8 ROPS and a texture filtering rate of 16 per clock. The above specs combined give the GTS a 32Gbps bandwidth with a fill rate of 10.8GT/s with the 8600 GT reaching 22.4GB/s and 8.6GT/s. These reduced specifications not only allow Nvidia to produce the 8600 for a lower cost than the 8800 series they also allow the card to run at a reduced power level (71w for the GTS and 43w for the GT). Both of these ratings are within the power level that can be passed through the PCI express slot however the GTS still comes with a 6 pin power connector for added stability. The low power requirement also means that less heat is generated by the card the result of which is single slot cooling on all but one of the models we have seen so far.

It’s not just the clocks and number of stream processors that are different in the 8600; there are also a number of improvements to the 8800 series design. Firstly the 8600 GTS is the first card to provide HDCP over Dual-Link DVI. This is also possible with the GT however HDCP is at the discretion of each partner on that specific product. The next improvement to the card comes in the shader ops per clock specification. The 8800 texture processors can do 4 texture addresses and 8 filtering ops per clock where as the 8600 texture processors can do 8 texture addresses and 8 filtering ops per clock which permits a greater number of texture locations to be sampled per clock. Finally, and most importantly the 8600 series cards feature the second generation video processing engine which for home cinema users is the best feature to be released on a card in quite some time.

The new video processing engine adds features to the 8600 which are not present on other products (including the 8800 series), here are the two main features:

BSP Engine: A dedicated H.264 processor which is designed to take 100% of the video processing tasks away from the CPU and on to the GPU.

AES128 Engine: Onboard hardware decrypt of protected content

An improved video processor is also included which features more advanced video post processing algorithm’s. We will look at the result of these features later in the review however it’s safe to say the results of this are nothing short of staggering. There is only one caveat to PureVideo HD at the moment and that is the feature only being available to Vista users until at least July this year.