New architecture

As we just mentioned, the new GeForce GPUs are fundamentally built on the same basic architecture already found today in the GeForce 8800 family, the only difference is that the new GeForce GPUs have been modified in order to be cheaper to produce. For instance, the G84 GPU used in the GeForce 8600 contains less than half the number of transistors as the G80 GPU used in the GeForce 8800s: just 289 million in G84 versus 681 million in G80. To further reduce production costs, the new GPUs are also built on TSMC’s smaller 80-nm manufacturing process.

Because these new GPUs are based on the same architecture as GeForce 8800, all of the key innovations found in G80 are also present in G84. NVIDIA relies on the same unified shading architecture with stream processors that run independent of the rest of the graphics core, and G84 continues to support NVIDIA’s Lumenex AA engine. Let’s look over the specs:

The GeForce 8600s

GeForce 8600 GT/GTS Specifications
	GeForce 8600 GTS	GeForce 8600 GT
GPU	G84	G84
Core Clock	675MHz	540MHz
Shader Clock (Stream Processors)	1.45GHz	1.19GHz
# of Stream Processors	32	32
Memory Clock Speed	1.0GHz	700MHz
Memory Interface	128-bit	128-bit
Memory Bandwidth	32GB/sec	22.4GB/sec
Memory Size	256MB	256MB
Texture Fill-Rate	10.8 Gigatexels/sec	8.6 Gigatexels/sec
HDCP Support	Yes	Optional

The GeForce 8600 GTS reference board

Front view of the 8600 GTS

As you can see, the biggest difference between the GeForce 8600 GTS and the GT lies in clock speeds, with the shaders on the 8600 GTS running nearly 300MHz faster than the GeForce 8600 GTS at 1.45GHz, while the GTS graphics core itself is 135MHz higher. With the higher speeds come higher power and cooling requirements and thus the GeForce 8600 GTS requires an external power connection. According to NVIDIA the GeForce 8600 GTS board draws up to 71 watts of power, while the GeForce 8600 GT has a maximum power draw of just 43 watts.

As you can see in the shots of the GeForce 8600 GTS reference board, the GTS also requires beefier cooling. Fortunately we can report that the GeForce 8600 GTS reference cooler ran quietly in our testing: NVIDIA equips the board with a variable speed fan but even under load when overclocking, the board’s fan never ran at max speed other than during system bootup.

GeForce 8600 GT reference board

Top of the GeForce 8600 GT

In terms of pricing, the GeForce 8600 GTS carries an MSRP of $199-$229, while the GeForce 8600 GT retails for $149-$159. Both cards ship with two dual-link DVI connectors as well as video-out (S-Video out is supported natively, while component out is provided via dongle).HDCP support is a requirement for all GeForce 8600 GTS cards, regardless of manufacturer, while HDCP support is an optional feature for the GeForce 8600 GT that NVIDIA leaves to their individual board partners.

GeForce 8500 GT

GeForce 8500 GT Specifications
Stream Processors	16
Core Clock Speed	450MHz
Shader Clock Speed	900MHz
Memory Clock Speed	400MHz
Memory Amount	512MB or 256MB DDR2
Memory Interface	128-bit
Memory Bandwidth	12.8GB/sec
Texture Fill-Rate	3.6 Gigatexels/sec
HDCP	Optional

Carrying a price tag in the $89-$129 range, the GeForce 8500 GT is the cost-reduced version of the GeForce 8600. It’s based on NVIDIA’s G86 GPU, shipping with slower clock speeds and with half the number of stream processors. This particular change reduces transistor count down to just 210 million. We don’t have one of these boards available for review today, but we will be taking a closer look at it once samples are available.

GeForce 8500 GT reference design

Simple cooling on the 8500 GT reference board