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ATI's Radeon 9600 Pro GPU

One step forward, two steps back?

HIGH-END GRAPHICS CARDS like NVIDIA's GeForce FX 5800 Ultra and ATI's Radeon 9800 Pro attract all manner of adoring fans and groupies, but only a select few can really afford to drop a fistful of Benjamins on these pricier upgrades. Hard-core gaming enthusiasts may always want the fastest available graphics cards, but for the rest of us, more reasonably-priced mid-range graphics cards can still offer buttery smooth frame rates in today's games. Heck, many of today's mid-range graphics cards can dish out more than 60 frames per second at high resolutions with antialiasing and anisotropic filtering enabled.

For the last several months, ATI's Radeon 9500 Pro has dominated the graphics card scene for gaming enthusiasts looking for the best bang for their graphics card dollar. We were thoroughly impressed with the Radeon 9500 Pro when we reviewed it back in November, and the card has been our mid-range graphics card pick ever since. Along the way, NVIDIA has tried to mount an offensive with its GeForce FX 5600, but those cards have yet to materialize in retail. In fact, only a small number of GeForce FX 5600 reviews have slipped onto the web, and thus far it doesn't look like the card poses a serious threat to the Radeon 9500 Pro.

Still, without a readily available competitor for the Radeon 9500 Pro, ATI has decided to refresh its mid-range offering with a new card, the Radeon 9600 Pro, based on the new RV350 GPU. The RV350 features all the swanky DirectX 9 features you'd expect from one of ATI's latest Radeons, but it has only half as many pixel pipelines, pixel shaders, and vertex engines as the R300 chip in the 9500 Pro. Of course, the Radeon 9600 Pro isn't totally neutered. The 0.13-micron RV350 GPU runs at a cool 400MHz, which is faster than even ATI's flagship Radeon 9800 Pro.

Has ATI juggled pixel pipelines and clock speeds well enough for the Radeon 9600 Pro to inherit the mid-range graphics leader mantle from its sibling? Keep reading to find out.

What's different?
The biggest news behind ATI's RV350 graphics chip is, perhaops, the 0.13-micron process technology being used to fabricate the chip. The move to a 0.13-micron process allows ATI to fit more chips on a silicon wafer, which should make the RV350 a more profitable chip than its predecessors if yields are good. Moving to a 0.13-micron process also decreases the RV350's power requirements, so cards built using the chip won't need auxiliary power connectors and should run cooler than equivalent chips built using 0.15-micron technology.

Of course, a 0.13-micron manufacturing process doesn't guarantee a cool-running graphics chip¬ójust look at the GeForce FX 5800 Ultra's Dustbuster. Fortunately, the RV350 does run cool. The Radeon 9600 Pro has one of the smallest active GPU heat sink/fan combos I've ever seen. In fact, I'd bet the chip will run at its full clock speed with only a slightly beefier passive heat sink.

Apart from the process technology used in its fabrication, the RV350 is very similar to ATI's R300 chip, which powers the Radeon 9500 and 9700 lines. The RV350 has full support for DirectX 9, pixel and vertex shader versions 2.0, and floating point data types for pixels and texture. However, the 9600 incorporates some performance tweaks from ATI's new R350 GPU (used in the Radeon 9800 Pro). There are a few key differences between the old R300 and the new RV350 worth noting.

  • Fewer pipes - Ever-cooperative when it comes to divulging the internal structure of its graphics chips, ATI has revealed that the RV350 has four pixel pipelines, each of which is capable of laying down a single texture per rendering pass. Because it has only four pipelines, the RV350 also has only four pixel shaders.

    Clock for clock, the RV350 should have half the fill rate of ATI's 8-pipe R3x0-series graphics chips and roughly half the pixel shader performance. To compensate for this pipeline disadvantage, ATI is ramping up the RV350's clock speeds, which should be relatively easy to do given the chip's 0.13-micron die.

  • Memory controller optimizations - Like the Radeon 9500 Pro, the Radeon 9600 Pro's memory bus is 128 bits wide, but the memory controllers used with each card are quite different. Because the R300 was originally designed for the Radeon 9700 Pro's 256-bit memory bus, the chip didn't make very efficient use of the Radeon 9500 Pro's 128-bit memory bus. For the Radeon 9600 Pro, ATI has specifically optimized the RV350's memory controller for a 128-bit memory interface. As a result, the Radeon 9600 Pro should make more efficient use of its available memory bandwidth than the Radeon 9500 Pro.

  • 8:1 Z-compression - The RV350 is ATI's first graphics chip to use 8:1 Z-compression, which should make the Radeon 9600 Pro even more efficient when it comes to memory bandwidth usage. By comparison, ATI's R300 GPU peaked at a 6:1 Z-compression ratio.

  • No F-buffer - Unlike ATI's high-end R350 chip, the RV350 doesn't have an F-buffer. Without an F-buffer, the Radeon 9600 Pro will be unable to handle shader programs more complex than what's called for by Microsoft's DirectX 9 spec, but it's still unclear how much of a limitation that will be in the real world. It will probably be some time before games exploit all of DirectX 9's shader capabilities, much less move beyond them. You can read more about what exactly an F-buffer is and what it does in our Radeon 9800 Pro review.
Now that we've gone over the important differences between ATI's RV350 GPU and its precursor, let's check out pictures of the Radeon 9600 Pro itself.

ATI's Radeon 9600 Pro reference board. Notice the lack of a auxiliary power connector.

The Radeon 9600 Pro from the rear, and oddly not in red.

The Radeon 9600 Pro's teensy weensy GPU cooler.

BGA memory chips from Samsung

Now, on to the benchmarks!