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TR interviews NVIDIA's Tony Tamasi

We grill NVIDIA about the GeForce 6 series

AS NVIDIA'S VICE PRESIDENT OF Technical Marketing, Tony Tamasi is more than just a marketing guy. He listens to customer feedback, helps define product specs, and then once the products are ready to roll, he acts as NVIDIA's liason and chief technical evangelist to the rest of the world. As you might imagine, he's had his hands full with the launch of the GeForce 6 series of GPUs, but he was kind enough to take time and answer some of our questions about NVIDIA's impressive new graphics processors.

Dates and details on the GeForce 6800 family

When will the GeForce 6800 Ultra arrive in stores?

Tamasi: By Memorial Day the 6800 Ultra will be available, and by July 4th, the full line of the 6800 series will be broadly available.

On the non-Ultra, how much memory will it have?

Tamasi: The $299 card?


Tamasi: That's actually up to the add-in card guys. There will be versions, I suspect, with 128 and 256MB, but that's more up to the add-in card guys than us, really.

Will that card have a 256-bit path to memory?

Tamasi: Yes it will.

Will it be DDR, DDR2, or DDR3 memory?

Tamasi: DDR1.

That combination of specs sounds like a tall order at $299. Can you guys make money selling it at that price?

Tamasi: If we couldn't, we wouldn't. [Laughter.]

We've heard that the GeForce 6800 Ultra GPU is 222 million transistors. How do you guys count transistors? Do you count all SRAM/cache, etc?

Tamasi: The only way we really know how to give an accurate transistor count is to count up all transistors on the chip, and that's everything. So that number includes caches, FIFOs, register files. It's all transistors. It's not just logic transistors.

Are you willing to divulge die sizes?

Tamasi: No, we don't typically divulge that stuff. It's big. [Laughter.]

Are you counting the same way for this one as for the NV30 series and past GPUs?

Tamasi: Yep. We've counted transistors the same way since we've talked about transistor counts. In fact, I'm not sure why anyone would ever throw out a transistor count for a chip that wasn't actually the transistor count of the chip.

Edge antialiasing

We noticed some interesting things about GeForce 6-series antialiasing in our review. Is the GeForce 6800's 8X antialiasing mode 4X supersampling plus 2X multisampling?

Tamasi: The current mode that's actually in the control panel is a 4X super/2X multi, and that will work in both OpenGL and D3D. We actually do have a 4X multi/2X super mode that a driver, probably within the next few weeks, is going to enable as well.

Does GeForce 6800 antialiasing do anything at scan-out that won't be picked up in screenshots? If so, what is it doing and in which modes?

Tamasi: The resolve pass—when you typically multisample you have to do a resolve pass—can either be done as another pass in the frame buffer or at scan-out. In the case of, like, if you're doing, say, 4X multisampling, that resolve pass is actually done what we call "on the fly." We don't take a separate pass and write another buffer.

So if you take screenshots, you need to... there's a couple of utilities that will do the right thing and a couple of them which will not do the right thing. In fact, our drivers now basically do the right thing. In other words, when you grab a frame, it will give you a a post-resolve image as opposed to a non-multisampled image.

Now, does that apply in all your multisampled modes?

Tamasi: Yeah. This resolve on the fly technology works for any multisampling mode.

What about screenshots from 3DMark03? When you use its image quality tool, does it produce the correct output?

Tamasi: If you select AA with 3DMark, then you'll get the correct frame grabs.

ATI has touted "gamma-correct blending" for antialiasing in the R300 series. Does the GeForce 6800 Ultra have this feature, and if not, why not?

Tamasi: It does, and I want to be really specific about this, because there's a lot of confusion about it. There's a great deal of difference between gamma correction and gamma adjustment. What ATI does is do a gamma adjustment to gamma 2.2, which can be correct depending on your display, and that's essentially what we do, as well. Gamma correction would typically would mean you could do an adjustment to any gamma, and that would require a shader pass.