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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  • Pumpkinierre - Wednesday, May 5, 2004 - link

    Sorry, scrub that last one. I couldnt help it. I will reform.
  • Pumpkinierre - Wednesday, May 5, 2004 - link

    So, which is better: a64 at 2Gig or P4 at 3.2?
  • jibbo - Wednesday, May 5, 2004 - link

    "Zobar is right; contra Jibbo, the increased flexibility of PS3 means that for many 2.0 shader programs a PS3 version can achieve equivalent results with a lesser performance hit."

    I think you're both still missing my point. There is nothing that says PS3.0 is faster than PS2.0. You are both correct that it has to potential to be faster, though you both assume that a first generation PS3.0 architecture will perform at the same level as a refined PS2.0 architechture.

    PS3.0 is one of the big reasons that nVidia's die size and transistor count are bigger than ATI's. The additional power drain (and consequently heat dissipation) of those 40M transistors also helps to limit the clock speeds of the 6800. When you're talking about ALU ops per second (which dominate math-intensive shaders), these clock speeds become very important. A lot of the 6800's speed for PS3.0 will have to be found in the driver optimizations that will compile these shaders for PS3.0. Left to itself, ATI's raw shader performance still slaughters nVidia's.

    They both made trade-offs, and it seems that ATI is banking that PS3.0 won't be a dealbreaker in 2004. Only time will tell....
  • Phiro - Wednesday, May 5, 2004 - link

    K, I found the $400M that the CEO claimed. He also claimed $400M for the NV3x core as well. It seemed more as a boast than anything, not particularly scientific or exact.

    In any case, ATI supposedly spent $165-180M last year (2003) on R&D, with an estimated increase of 100% for this year. How long has the 4xx core been in development?

    Regardless, ultimately we the consumers are the winners. Whether or not the R&D spent pans out will play out over the next couple years, as supposedly the nv4x core has a 24 month lifespan.

  • 413xram - Wednesday, May 5, 2004 - link

    If you watch nvidia's launch video on their site they mention the r&d costs for their new card.
  • RyanVM - Wednesday, May 5, 2004 - link

    What ever happened to using ePSXe as a video card benchmark?
  • Phiro - Wednesday, May 5, 2004 - link

    Well, Nvidia may have spent $400M on this (I've never seen that number before but we'll go with it I guess) but they paid themselves for the most part.

    ATI's cost can't be too trivialized - didn't they drop a product design or two in favor of getting this out the door instead? And any alteration in the architecture of something doesn't really qualify as a hardware "refresh" in my book - a hardware refresh for an OEM consists of maybe one speed notch increase in the RAM, new bios, larger default HD, stuff like that. MLK is what Dell used to call it - Mid Life Kick.
  • retrospooty - Wednesday, May 5, 2004 - link

    "Precisely. By the time 512mb is useful, the card will be too slow for it to matter, and you'd need a new card any way."

    True...

    Both cards perform great, both have wins and losses depending on the game. The deciding factor will be price and power requirements.

    Since prices will adjust downward, at a fairly equal rate, that leaves power. With Power requirements being so incredibly high with the NV40, that leans me toward ATI.

    413xram also has a good point above. For Nvidia, this is a 400 million dollar new chip design. For ATI, this was a refresh of an old design to add 16 pipes, and a few other features. After the losses NV took with the heavily flawed NV30 and 35 , they need a financial boom, and this isnt it.

  • mattsaccount - Wednesday, May 5, 2004 - link

    There are no games available today that use 256mb of video RAM, let alone 512mb. Even upper-high-end cards routinely come with 128mb (e.g. Geforce FX 5900, Radeon 9600XT). It would not make financial sense for a game developer to release a game that only a small fraction of the community could run acceptably.

    >> I have learned from the past that future possibilties of technology in hardware does nothing for me today.

    Precisely. By the time 512mb is useful, the card will be too slow for it to matter, and you'd need a new card any way.
  • 413xram - Wednesday, May 5, 2004 - link

    #64 Can you explain "gimmick"?

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