NVIDIA's 1.4 Billion Transistor GPU: GT200 Arrives as the GeForce GTX 280 & 260
by Anand Lal Shimpi & Derek Wilson on June 16, 2008 9:00 AM EST- Posted in
- GPUs
GT200 vs. G80: A Clock for Clock Comparison
The GT200 architecture isn't tremendously different from G80 or G92, it just has a lot more processing power. The comparison below highlights the clock for clock difference between GT200 and its true predecessor, NVIDIA's G80. We clocked both GPUs at 575MHz core, 900MHz memory and 1350MHz shader, so this is a look at the hardware's architectural enhancements combined with the pipeline and bus width increases. The graph below shows the performance advantage of GT200 over G80 at the same clock speeds:
Clock for clock, just due to width increases, we should be at the very worst 25% faster with GT200. This would be the case where we are texture bound. It is unlikely an entire game will be blend rate bound to the point where we see greater than 2x speedups, and while test cases could show this real world apps just aren't blend bound. More realistically, the 87.5% increase in SPs will be the upper limit on performance improvements at the same clock rate. We see our tests behave within these predicted ranges.
Based on this, it appears that Bioshock is quite compute bound and doesn't run into many other bottlenecks when the burden is eased. Crysis on the other hand seems to be limited by more than just compute as it didn't benefit quite as much.
The way compute has been rebalanced does affect the conditions under which performance will benefit from the additional units. More performance will be available in the case where a game didn't just need more compute, but it needed more computer per texture. The converse is true when a game could benefit from more compute, but only if there was more texture hardware to feed them.
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strikeback03 - Tuesday, June 17, 2008 - link
So are you blaming nvidia for games that require powerful hardware, or just for enabling developers to write those games by making powerful hardware?InquiryZ - Monday, June 16, 2008 - link
Was AC tested with or without the patch? (the patch removes a lot of performance on the ATi cards..)DerekWilson - Monday, June 16, 2008 - link
the patch only affects performance with aa enabled.since the game only allows aa at up to 1680x1050, we tested without aa.
we also tested with the patch installed.
PrinceGaz - Monday, June 16, 2008 - link
nVidia say they're not saying exactly what GT200 can and cannot do to prevent AMD bribing game developers to use DX10.1 features GT200 does not support, but you mention that"It's useful to point out that, in spite of the fact that NVIDIA doesn't support DX10.1 and DX10 offers no caps bits, NVIDIA does enable developers to query their driver on support for a feature. This is how they can support multisample readback and any other DX10.1 feature that they chose to expose in this manner."
Now whilst it is driver dependent and additional features could be enabled (or disabled) in later drivers, it seems to me that all AMD or anyone else would have to do is go through the whole list of DX10.1 features and query the driver about each one. Voila- an accurate list of what is and isn't supported, at least with that driver.
DerekWilson - Monday, June 16, 2008 - link
the problem is that they don't expose all the features they are capable of supporting. they won't mind if AMD gets some devs on board with something that they don't currently support but that they can enable support for if they need to.what they don't want is for AMD to find out what they are incapable of supporting in any reasonable way. they don't want AMD to know what they won't be able to expose via the driver to developers.
knowing what they already expose to devs is one thing, but knowing what the hardware can actually do is not something nvidia is interested in shareing.
emboss - Monday, June 16, 2008 - link
Well, yes and no. The G80 is capable of more than what is implemented in the driver, and also some of the implemented driver features are actually not natively implemented in the hardware. I assume the GT200 is the same. They only implement the bits that are actually being used, and emulate the operations that are not natively supported. If a game comes along that needs a particular feature, and the game is high-profile enough for NV to care, NV will implement it in the driver (either in hardware if it is capable of it, or emulated if it's not).What they don't want to say is what the hardware is actually capable of. Of course, ATI can still get a reasonably good idea by looking at the pattern of performance anomalies and deducing which operations are emulated, so it's still just stupid paranoia that hurts developers.
B3an - Monday, June 16, 2008 - link
@ Derek - I'd really appreciate this if you could reply...Games are tested at 2560x1600 in these benchmarks with the 9800GX2, and some games are even playable.
Now when i do this with my GX2 at this res, a lot of the time even the menu screen is a slide show (often under 10FPS). Epecially if any AA is enabled. Some games that do this are Crysis, GRID, UT3, Mass Effect, ET:QW... with older games it does not happen, only newer stuff with higher res textures.
This never happened on my 8800GTX to the same extent. So i put it down to the GX2 not having enough memory bandwidth and enough usable VRAM for such high resolution.
So could you explain how the GX2 is getting 64FPS @ 2560x1600 with 4x AA with ET:Quake Wars? Aswell as other games at that res + AA.
DerekWilson - Monday, June 16, 2008 - link
i really haven't noticed the same issue with menu screens ... except in black and white 2 ... that one sucked and i remember complaining about it.to be fair i haven't tested this with mass effect, grid, or ut3.
as for menu screens, they tend to be less memory intensive than the game itself. i'm really not sure why it happens when it does, but it does suck.
i'll ask around and see if i can get an explaination of this problem and if i can i'll write about why and when it will happen.
thanks,
Derek
larson0699 - Monday, June 16, 2008 - link
"Massiveness" and "aggressiveness"?I know the article is aimed to hit as hard as the product it's introducing us to, but put a little English into your English.
"Mass" and "aggression".
FWIW, the GTX's numbers are unreal. I can appreciate the power-saving capabilities during lesser load, but I agree, GT200 should've been 55nm. (6pin+8pin? There's a motherboard under that SLI setup??)
jobrien2001 - Monday, June 16, 2008 - link
Seems Nvidia finally dropped the ball.-Power consumption and the price tag are really bad.
-Performance isnt as expected.
-Huge Die
Im gonna wait for a die shrink or buy an ATI. The 4870 with ddr5 seems promising from the early benchmarks... and for $350? who in their right mind wouldnt buy one.