NVIDIA G80: Architecture and GPU Analysis
Posted: 2006-11-08 02:45pm
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Haha! I KNEW that was going to be your reaction! Don't worry, I plan on gathering some data from BF2142, Oblivion and NWN2 tonight with my GX2, and again tomorrow on the GTX (don't expect a lot, though, I want to play with my new toy).Ace Pace wrote:Fuck you, fuck you hard. You WILL bench that thing under realistic conditions.
Am I reading this right? Is this basicly free AA aslong as the ROPs arn't busy actully writing data to the display?Ah, the ROP hardware. In terms of base pixel quality it's able to perform 8x multisampling using rotated or jittered subsamples laid over a 4-bit subpixel grid, looping through the ROP taking 4 multisamples per cycle. It can multisample from all backbuffer formats too, NVIDIA providing full orthogonality, including sampling from pixels maintained in a non-linear colour space or in floating point surface formats. Thus the misunderstood holy grail of "HDR+AA" is achieved by the hardware with no real developer effort. Further, it can natively blend pixels in integer and floating point formats, including FP32, at rates that somewhat diminish with bandwidth available through the ROP (INT8 and FP16 full speed (measured) and FP32 half speed). Each pair of ROPs share a single blender (so 12 blends per cycle) from testing empirically.
Sample rates in the ROP are hugely increased over previous generation NVIDIA GPUs, a G80 ROP able to empirically sample Z 8 times per clock (4x higher than G7x ever could), with that value scaling for every discrete subsample position, per pixel, bandwidth permitting of course. Concluding 'free' 4xMSAA from the ROP with enough bandwidth is therefore an easy stretch of the imagination to make, and the advantages to certain rendering algorithms become very clear. The 24 ROPs in a full G80 are divided into partitions of 4 each, each partition connecting to a 64-bit memory channel out to the DRAM pool for intermediary or final storage.
anisotropic filtering is effectively pretty much free, depending on your game and target resolution of course.
I would suspect ATI and NVidia have enough spies in each other's operations or at the very least a good enough team of reverse engineers to compete with anything the other throws out.Arrow wrote: [...] no one knew what the G80 was going to be until a month ago, so ATI may well have some surprises in store.
Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.Captain tycho wrote:I really want one of these, but I simply can't justify spending 500+ dollars on a video card when the one I have now does everything I need it to do at a very acceptable speed, and when DX10 cards aren't that far off.
Well, that and a 680 million transistor GPU at 90nm probably has rather low yields. By comparison, the newest x86 CPUs have less than 300 million at 65 nm. RAM for GPUs is also more expensive as well (being specialized, high-performance parts)NRS Guardian wrote:Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.
phongn wrote:Well, that and a 680 million transistor GPU at 90nm probably has rather low yields. By comparison, the newest x86 CPUs have less than 300 million at 65 nm. RAM for GPUs is also more expensive as well (being specialized, high-performance parts)NRS Guardian wrote:Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.
Architecting such a massive GPU has taken NVIDIA a great deal of time and money, four years and $475M to be exact.
The 8800 GTX isn't that much more expensive than the 7800 GTX when it launched (I paid $579 for an OC'ed version when it launched). In fact, you could possibly argue that its cheaper, since I needed two 7800 GTXs to drive my 24" LCD (1920x1200), while it looks I'll only need one 8800 GTX for the same display.phongn wrote:Well, that and a 680 million transistor GPU at 90nm probably has rather low yields. By comparison, the newest x86 CPUs have less than 300 million at 65 nm. RAM for GPUs is also more expensive as well (being specialized, high-performance parts)NRS Guardian wrote:Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.
No kidding.phongn wrote:Well, that and a 680 million transistor GPU at 90nm probably has rather low yields. By comparison, the newest x86 CPUs have less than 300 million at 65 nm. RAM for GPUs is also more expensive as well (being specialized, high-performance parts)NRS Guardian wrote:Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.
Eighty. From a 300mm wafer. And thats just gross numbers...Nvidia's isn't handing out exact die size measurements, but they claim to get about 80 chips gross per wafer.
That's comparing apples and oranges. We're comparing stock board to stock-board, not pre-overclocked variants or SLI.Arrow wrote:The 8800 GTX isn't that much more expensive than the 7800 GTX when it launched (I paid $579 for an OC'ed version when it launched). In fact, you could possibly argue that its cheaper, since I needed two 7800 GTXs to drive my 24" LCD (1920x1200), while it looks I'll only need one 8800 GTX for the same display.
Mostly this was due to higher costs associated with doing transistor level design apparently.Ace Pace wrote:phongn wrote:Well, that and a 680 million transistor GPU at 90nm probably has rather low yields. By comparison, the newest x86 CPUs have less than 300 million at 65 nm. RAM for GPUs is also more expensive as well (being specialized, high-performance parts)NRS Guardian wrote:Uh... this is a DX10 card, the first DX10 card to be released. That's why it's so expensive.Architecting such a massive GPU has taken NVIDIA a great deal of time and money, four years and $475M to be exact.
Still, the 7800 GTX was a somewhat anomalous case because there were so many available on launch and priced dropped by like $75 under MSRP scant weeks after release. Top end cards have been pretty consistently priced at $600 or so at release, and this is no exception. The GeForce 3 came out at $600, after all.phongn wrote:That's comparing apples and oranges. We're comparing stock board to stock-board, not pre-overclocked variants or SLI.Arrow wrote:The 8800 GTX isn't that much more expensive than the 7800 GTX when it launched (I paid $579 for an OC'ed version when it launched). In fact, you could possibly argue that its cheaper, since I needed two 7800 GTXs to drive my 24" LCD (1920x1200), while it looks I'll only need one 8800 GTX for the same display.