Radeon X1800 GTO Specification
Let's take a look at the configuration and spec for R520 that ATI set out for X1800 GTO, compared to NVIDIA G73.| ATI R520 vs G73; X1800 GTO vs 7600 GT | ||
|---|---|---|
| GPU | ATI R520 | NVIDIA G73 |
| Process and Fabricator | 90nm @ TSMC, 90GT w/ low-k | |
| Die Size | 288mm² | 125mm² |
| Transistor Count | 321M | 177M |
| DirectX Shader Model | Shader Model 3.0 | |
| Basic Configuration (VP/FP/ROP) | 8/12/12 | 5/12/8 |
| Vertex Shader Info | VS3.0 5D FP32, co-issue MADD, branch |
VS3.0 5D FP32, co-issue MADD, branch, tex |
| Fragment Processor Info | PS3.0 4D FP32, dual and co-issue MADD/ADD, branch, tex |
PS3.0 4D FP32, dual and co-issue MADD/MADD, branch, tex |
| ROP Info | 6x FX8/FX16/FP16/Int10 MSAA (2 subsamples/cycle) 2x Z-only rate FP/FX blender (inc. FP16) |
4x FX8/FX16 MSAA (2 subsamples/cycle) 2x Z-only rate, 2x colour-only rate FP/FX blender (inc. FP16) |
| Texture processing | 12 FP32 address units, 12 samplers Bi/Tri/Aniso (128-tap) |
12 FP32 address units¹, 12 samplers Bi/Tri/Aniso (128-tap), FP16 filtering |
| Memory Interface | 256-bit, 8 memory channels GDDR->GDDR3 |
128-bit, 2 memory channels GDDR->GDDR3 |
| Display output | 2x dual-link DVI TMDS, ATI Avivo | 1x dual-link DVI TMDS, 1x single-link DVI TMDS, NVIDIA PureVidio |
| Notes | ¹Texture address shared exclusive with first sub-ALU instruction issue | |
[advert] ATI's choice to use R520 in a mid-range product designed to compete with the G73-powered 7600 GT is somewhat telling. It's a big chip, somewhat at odds with the ethos behind a money-making part, but with ATI finding high-clocked RV530 uncompetitive, using a 'big gun' in cut-down form is needed.
Clocked at 500/500 (slower than 7600 GT's 560/700), Radeon X1800 GTO therefore uses its memory controller, VS unit count and 1:1 FP:ROP ratio to take the fight to 7600 GT. With a 256-bit external path to on-board memory and 12 ROPs, to pair with the same 8 vertex units of higher-spec Radeon X1800s, the GTO competes on paper in the performance stakes.
In terms of possible image quality, R520 has the edge over G73, allowing Radeon X1800 GTO to draw better looking final pixels. A higher level of high-quality, always gamma-correct anti-aliasing, the possibility of largely rotationally-invariant texture filtering, and NVIDIA-matching 'adaptive' AA mostly see to that.
Then you have a pair of dual-link TMDS transmitters on the GPU and support for ATI's Avivo video and display technology and there's no disputing that features-wise and on paper, Radeon X1800 GTO looks mightily impressive. Supporting Shader Model 3.0 and ATI Crossfire, it's the most feature complete mid-range graphics product on the market today.
As long as it competes performance-wise, there should be little to stop a hearty recommendation on the face of it all. Let's look at Sapphire's example before examining performance to see if the execution matches the promise of this initial exam.
