First test: Nvidia GeForce 8600 GTS & GT

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Posted on 17 Apr 2007 at 14:56

Nvidia has launched one of the most eagerly anticipated GPUs to date, the 8600 - and PC Pro has put two new cards through our extensive tests.

Evesham's Solar 8600GTS PC is the first system to use these promising new cards - read our full review here.

With previous mid-range GeForce GPUs garnering huge praise for offering great performance at very reasonable prices, the new chip has much to live up to. At launch there are two flavours of GeForce 8600 - the GTS and the GT - with the former being the faster chip.

The architecture

They're architecturally identical, both containing 289 million 80nm transistors, most of which are from the 32 stream processors. These have a unified shader architecture to allow them to process any kind of game data, from the usual vertex and pixel to the new geometry shaders and even physics calculations. Both chips also have 8 Render Output Processors, allowing them to send 8 finished pixels to the frame buffer per clock.

This frame buffer is set to be 256MB on both versions (though expect variations such as 512MB or 128MB), with a 128-bit interface to help data flow to and from this graphics memory. That's enough for most modern games, although texture-heavy DirectX 10 games will likely push this to the limit.

The products are differentiated by their clock speeds, with the GTS clocked much higher than the GT. The 32 stream processors of the GTS run at a breakneck 1.45GHz, which is even faster than those running in the top-end 8800 GTX. The 8600 sees a slight improvement to these stream processors too, with the ability to address twice as many (eight) texture locations per clock as an 8800 stream processor.

Around this super-quick shader core are the set-up engines and thread dispatch units to feed it, and those 8 ROPs to deal with the results. This collection of sub-units (strangely referred to by Nvidia as the GPU 'core') run at a stellar 675MHz, again faster than the equivalent parts of an 8800GTX. And to match those super-high clock speeds in the 8600 GTS GPU, it'll ship with RAM running at 1GHz, a feat matched by only the top-end ATi Radeon X1950 XTX.

The 8600 GT has more modest clocks, with its 32 stream processors running at 1.19GHz and its 'core' at 540MHz, while its RAM runs at a more modest 700MHz. And while HDCP is guaranteed with the 8600 GTS, it's a card-maker option with the GT so read the specifications carefully.

Game performance

But enough of the theory, how do the two cards perform? The simple answer is very well: at our Standard settings (see below for details) only the toughest of games and settings brought either the GTS or the GT to an unplayable frame rate.

The GTS raced to a score of 53fps in Far Cry, 36fps in Call of Duty 2 and a fairly impressive 24fps in Elder Scrolls IV: Oblivion. Dropping the antialiasing and anisotropic filtering (AA and AF) from the latter two tests boosted the score to 43fps and 53fps respectively; pretty high scores for even top-end DirectX 9 graphics cards.

The GT predictably fared less well, but still managed a healthy 42fps in Far Cry, although Call of Duty 2 dropped to 29fps and Oblivion to 21fps. Again, losing the AA and AF brought a huge performance gain, with the latter two games becoming playable with scores of 35fps and a mighty 44fps respectively. At 1,280 x 1,024 the 8600 GT has enough clout to play even the toughest of games, but whether this will translate into DirectX 10 performance is anyone's guess - there's still no sign of any games being released in the next few months.