The Chip

R420 is a very power GPU in tight little package. ATI opted not to go with full DirectX 9.0 Shader Model 3.0 support in their latest GPU, but that doesn't mean that this chip doesn't pack a punch. Here's a breakdown of what's on the top of the line playing field now.

  NV38 NV40 R360 R420
Transistors
130M
222M
110M
160M
Core clock
475MHz
400MHz
412MHz
500MHz
Mem clock
950MHz
1.1GHz
900MHz
1.12GHz
Memory Bus
256bit
256bit
256bit
256bit
Vertex Pipelines
~4
6
4
6
Pixel Pipelines
4x2
16x1
8x1
16x1
Shader Model
2.0+
3.0
2.0
2.0+
Fab Process
130nm
130nm
150nm
130nm

  GeForce 6800 GT GeForce 6800 Ultra GeForce 6850 Ultra Radeon X800 Pro Radeon X800 XT PE
Price
$399
$499
$499+
$399
$499

The first thing we see is that R420 has the highest clock speed (giving it the highest peak fillrate), and it just edges out NV40 for memory speed. Of course, these theoretical numbers don't really translate directly into performance. In order to understand where performance comes from, we'll need to take a much closer look at the architecture.

Before we get in over our heads on this, it is important to differentiate the hardware itself from how the hardware looks in terms of a graphics API. Both NVIDIA and ATI, in presenting their hardware to us, have relied heavily on using the constructs of DirectX 9 to explain what's going on at different stages in the pipeline. This is useful in that we can understand how the hardware looks to the software, but there are some caveats. We will be keeping this in mind as we look over the new offerings from ATI and NVIDIA.

Index The R420 Vertex Pipeline
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  • saechaka - Tuesday, May 4, 2004 - link

    wow. very impressive. i was set on getting an nvidia but just don't know anymore
  • Phiro - Tuesday, May 4, 2004 - link

    The message is clear; Matrox has failed!
  • Brickster - Tuesday, May 4, 2004 - link

    Show me the money!
  • MemberSince97 - Tuesday, May 4, 2004 - link

    Advanced features are worthless if your driver team keeps breaking them..
  • f11 - Tuesday, May 4, 2004 - link

    kinda starting to feel sorry for nvidia now. each generation they stuff their cards with more feautures than they need to, end end up with a slower and more featured card. If anyone's expecting SM3 to be a big hit, remember that the original FX line had lots of extensions to DX9 and they never really made much a difference.

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