NVIDIA's GeForce 8800 (G80): GPUs Re-architected for DirectX 10
by Anand Lal Shimpi & Derek Wilson on November 8, 2006 6:01 PM EST- Posted in
- GPUs
Our DX9FSAAViewer won't show us the exact sample patterns for CSAA, but we can take a look at where ATI and NVIDIA are getting their color sample points:
| ATI |  |
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| G70 |  |
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| G80 |  |
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| G80* |  |
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*Gamma AA disabled
As we can see, NVIDIA's 8x color sample AA modes use a much better pseudo random sample pattern rather than a combination of two rotated grid 4xAA patterns as in G70's 8xSAA.
While it is interesting to talk about the internal differences between MSAA and CSAA, the real test is pitting NVIDIA's new highest quality mode against ATI's highest quality.
G70 4X G80 16XQ ATI 6X
Hold mouse over links to see Image Quality
G70 4X G80 16XQ ATI 6X
Hold mouse over links to see Image Quality
Stacking up the best shows the power of NVIDIA's CSAA with 16 sample points and 8 color/z values looking much smoother than ATI's 6xAA. Compared to G70, both ATI and G80 look much better. Now let's take a look at the performance impact of CSAA. This graph may require a little explanation to understand, but it is quite interesting and worth looking at.
As we move from lower to higher quality AA modes, performance generally goes down. The exception is with G80's 16x mode. Its performance is only slightly lower than 8x. This is due to the fact that both modes use 4 color samples alongside more coverage samples. We can see the performance impact of having more coverage samples than color samples by looking at the performance drop from 4x to 8x on G80. There is another slight drop in performance when increasing the number of coverage samples from 8x to 16x, but it is almost nil. With the higher number of multisamples in 8xQ, algorithms that require z/stencil data per sub-pixel may look better, but 16x definitely does great job with the common edge case with much less performance impact. Enabling 16xQ shows us the performance impact of enabling more coverage samples with 8x multisamples.
It is conceivable that a CSAA mode using 32 sample points and 8 color points could be enabled to further improve coverage data at nearly the same performance impact of 16xQ (similar to the performance difference we see with 8x and 16x). Whatever the reason this wasn't done in G80, the potential is there for future revisions of the hardware to offer a 32x mode with the performance impact of 8x. Whether the quality improvement is there or not is another issue entirely.
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DerekWilson - Thursday, November 9, 2006 - link
i'm sure there was a lot burried in there ... sorry if it wasn't easy to find.8800 gtx and gtx are both no louder than 7900 gtx. 1950 xtx still takes the cake for loudest graphics card around by a long shot -- especially after it heats up in a game.
crystal clear - Thursday, November 9, 2006 - link
My comments in Daily Tech on this subject-More "G80" Derivatives in February R
E: More info would be nice
By crystal clear on 11/8/06, Rating: 2
By crystal clear on 11/8/2006 8:03:43 AM , Rating: 2
If you link VISTA -SANTA ROSA platform-Core2DUO(merom)CPU line up(T7300,7500,7700 models)then a matching Graphics card
to complete the link.
So a G80 for laptops/notebooks?
The pairing of Intels Santa Rosa platform with Vista in the 2Q 07 is next big thing for the first tier notebook manufacturers & all they need is a matching G80 for this setup.
Unquote-
Nvidia currently caters to Desktop requirement/needs with the new G80 releases,wonder how the notebook/server versions will be-with Vista ofcourse.
yyrkoon - Thursday, November 9, 2006 - link
Vitual memory is probably a good thing for most cases, but in the graphics arena, this *could* potentially make for sloppy/ bad coding practises. Knowing a lot of game devers (some of which actually work for well known companies), I've heard them from time to time complain about maxing a 16x PCI-E pipe. What I'm trying to say here, is that while it would be a good thing for never having to run out of texture memory, but that system memory, and definately the swap disk can not hold a candle to the memory bandwidth that most Video cards are capable of. End result, is that you definately *will* get a performance hit. All this, and we already know the memory bandwidth capabilities of modern PCs, suffice it to say, the most we'll see from current systems is what ? 12-13K GB/s ? Even a 7800GS can do roughly 35 GB/s on card. A 7600GT ? 22GB/s ?Still I think Directx10 is a very good thing, and as I didnt read the whole article, perhaps a missed a little ? Reason being, I've been reading about Directx10 since April, and a friend of mine was privy to some of this information after an interview with ATI.
http://www.gamedev.net/reference/programming/featu...">http://www.gamedev.net/reference/programming/featu...
saratoga - Thursday, November 9, 2006 - link
I don't know how they threading really works, but its quite possible VM support is required in order to allow multiple threads to run without stepping all over each other,.saratoga - Thursday, November 9, 2006 - link
Sorry, should read "I don't know how THEIR threading works"falc0ne - Thursday, November 9, 2006 - link
I don't know what is the problem but I'm really unable to see the images within the latest articles from Anand...Can anyone give me a suggestion? What might be the cause of that?The thing is I'm really, really interested in these articles and I need to see those images. Thanks
yyrkoon - Thursday, November 9, 2006 - link
Oh, er, then in the options tab of Firefox, (tools->options->content) check the "load images" check box ;)falc0ne - Thursday, November 9, 2006 - link
well...it would've been simple but I'm afraid is not that...It might be the addblock extension from firefox, other than that I have nooo ideeea...Well I will use the IE tab option instead and load the pages using IE 7. Thanks anyway:)yyrkoon - Thursday, November 9, 2006 - link
Checked the exceptions list ? I know that firefox makes it really simple to block images from a site (to a point of being too easy).JarredWalton - Thursday, November 9, 2006 - link
If you've got AdBlock on Firefox, press Ctrl+Shift+A and you can see what it's blocking. If it blocks the images.anandtech.com stuff, you can then see which RegEx isn't working right and edit that.