The ATI RADEON 8500 and 7500

Both the ATI RADEON 8500 and 7500 are new video card entrants from ATI, but they have taken decidedly different routes in their overall design. The RADEON 8500 is the revolutionary product of the two, featuring a new R200 graphics engine designed to compete against the NVIDIA GeForce3 line. The RV200 core featured on the RADEON 7500 takes a more evolutionary approach similar to the GTS-Pro-ULTRA path NVIDIA took with the GeForce2 line. Each design has its pros and cons, mostly relating to price, performance and overall market positioning.

The RADEON 8500 matches the NVIDIA GeForce2/3 lines with quad rendering pipeline with dual texture units per pipeline. This physical chip format has become a virtual standard with developers and it may be a prime reason behind ATI abandoning the innovative (though hardly used) three texture units per pipeline of the previous RADEON video cards.

Where ATI really takes it to NVIDIA is with the RADEON 8500's 275 MHz core clock speed. While the 240 MHz GeForce3 Ti 500 entry may have closed the gap, ATI has (at least on paper) the fastest GPU on the market today. The RADEON 8500 is no slouch in the memory department, and features a matching 275 MHz DDR clock speed which again betters the GeForce3 Ti 500's default 250 MHz DDR speed. In terms of pure core/memory speeds, the RADEON 8500 certainly has some impressive specifications, even when compared to the best that NVIDIA has to offer.

Of course, comparing GPUs based only on their clock speeds is a spurious angle, since there are many aspects of performance far outside of engineering specs. The GPU design, the memory speed, bus and controller, and especially the software drivers can have a huge impact on performance. While a bit easier to quantify than video cards, we all know the fallacy of comparing an AMD Athlon, a Pentium 4 and a PowerPC G4 based only on their clock speeds. For a quick example, the RADEON 8500 features only a single-channel 128-bit memory controller, which is not as advanced as the pseudo-quad channel, Crossbar memory controller found on the GeForce3 cards.

The RADEON 7500 is a horse of a different color, as it's basically a die-shrink version of the current RADEON. This translates into a smaller core die, but one using the same two pipeline/three texture units per pipeline physical design. The previous RADEON GPU was produced using a 0.18-micron die, and the RADEON 7500 includes one produced using the smaller 0.15-micron process. Not that this is necessarily bad news, as we all know what kind of performance increases the Intel Pentium III gained by moving to a smaller die, as well as the potential for the upcoming crop of 0.13-micron CPUs from both AMD and Intel.

Naturally the rationale for the die shrink is to rack the core speeds as high as possible, which ATI has done to the tune of a whopping 290 MHz. Remember when we mentioned not taking pure clock speed as a indicator of 3D performance? Well, ATI has proven this statement, as the RADEON 7500 sports a 15 MHz higher clock speed than the RADEON 8500, but is positioned as a lower performance product.

At 230 MHz, the memory speed of the RADEON 7500 are not quite as robust, but the memory processing has been slightly refined to match the RADEON 8500. Basically, the overall impression we get from this card is of a super-charged RADEON DDR engine running on pure nitrous oxide. Whether the higher core and memory speeds can make up for its lack of architectural enhancements is something we'll have to answer a bit later on.

The following chart should help illustrate the mainstream ATI and NVIDIA models and the differences in basic hardware specifications between each:

Specification	Core Clock	Memory Clock (DDR)	Pipelines	TMUs
RADEON 8500	275 MHz	275 MHz (550 MHz)	4	2
GeForce3 Ti 500	240 MHz	250 MHz (500 MHz)	4	2
GeForce3	200 MHz	230 MHz (460 MHz)	4	2
GeForce3 Ti 500	175 MHz	200 MHz (400 DDR)	4	2
RADEON 7500	290 MHz	230 MHz (460 MHz)	2	3
GeForce2 ULTRA	250 MHz	230 MHz (460 MHz)	4	2
GeForce2 Ti	250 MHz	200 MHz (400 DDR)	4	2
GeForce2 Pro	200 MHz	200 MHz (400 DDR)	4	2