NVIDIA's GeForce 7800 GTX Hits The Ground Running
by Derek Wilson on June 22, 2005 9:00 AM EST- Posted in
- GPUs
No More Shader Replacement
The secret is all in compilation and scheduling. Now that NVIDIA has had more time to work with scheduling and profiling code on an already efficient and powerful architecture, they have an opportunity. This generation, rather than build a compiler to fit hardware, they were able to take what they've learned and build their hardware to better fit a mature compiler already targeted to the architecture. All this leads up to the fact that the 7800 GTX with current drivers does absolutely no shader replacement. This is quite a big deal in light of the fact that, just over a year ago, thousands of shaders were stored in the driver ready for replacement on demand in NV3x and even NV4x. It's quite an asset to have come this far with hardware and software in the relatively short amount of time NVIDIA has spent working with real-time compilation of shader programs.All these factors come together to mean that the hardware is busy more of the time. And getting more things done faster is what it's all about.
So, NVIDIA is offering a nominal increase in clock speed to 430MHz, just a little more memory bandwidth (256bit memory buss running at a 1.2GHz data rate), 1.33x vertex pipelines, 1.5x pixel pipelines, and various increases in efficiency. These all work together to give us as much as double the performance in extreme cases. If the performance increase can actually be realized, we are looking at a pretty decent speed increase over the 6800 Ultra. Obviously, in the real world we won't be seeing a threefold performance increase in anything but a bad benchmark. In cases where games are CPU limited, we will likely see a much lower increase in performance, but performance double that of the 6800 Ultra is entirely possible in very shader limited games.
In fact, EPIC reports that under certain Unreal Engine 3 tests they currently see two to 2.4x improvements in framerate over the 6800 Ultra. Of course, UE3 is not finished yet and there won't be games out based on the engine for a while. We don't usually like reporting performance numbers from software that hasn't been released, but even if these numbers are higher than we will see in a shipping product, it seems that NVIDIA has at least gotten it right for one developer's technology. We are very interested in seeing how next generation games will perform on this hardware. If we can trust these numbers at all, it looks like the performance advantage will only get better for the GeForce 7800 GTX until Windows Graphics Foundation 2.0 comes along and inspires new techniques beyond SM3.0 capabilities.
Right now, each triangle that gets fed through the vertex pipeline, there are many pixels inside the object that needs her help.
Bringing It All Together
Why didn't NVIDIA build a part with unified shaders?
Every generation, NVIDIA evaluates alternative architectures, but at this time they don't feel that a unified architecture is a good match to the current PC landscape. We will eventually see a unified shader architecture from NVIDIA, but it will not likely be until DirectX itself is focused around a unified shader architecture. At this point, vertex hardware doesn't need to be as complex or intricate as the pixel pipeline. As APIs develop more and more complex functionality it will be advantageous for hardware developers to move towards a more generic and programmable shader unit that can easily adapt to any floating point processing need.
As pixel processing is currently more important than vertex processing, NVIDIA is separating the two in order to focus attention where it is due. Making hardware more generic usually makes it necessarily slower, but explicitly targeting a specific aspect of something can often improve performance a great deal.
When WGF 2.0 comes along and geometry shaders are able to dynamically generate vertex data inside the GPU we will likely see an increased burden on vertex processing as well. Being able to programmatically generate vertex data will help to remove the burden on the system to supply all the model data to the GPU.
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Alx - Wednesday, June 22, 2005 - link
Face it, this launch isn't gonna hurt anyone except people with minds too small to accept that there is simply one more option than there was before. If you liked pc gaming yesterday, then there is no reason why this launch should make you stop liking it today. Unless you're a retarded buttbaby who can't handle choices. In that case please get a console and stop coming to this site.mlittl3 - Wednesday, June 22, 2005 - link
#82, WesleyWell that sucks that ya'll have lost your web editor for awhile. Especially when there is so much cool hardware coming out around now. In our research lab, we pass around our publications and conference posters to others in the group so that a fresh pair of eyes see them before they go live or to the journal editor. But of course, everyone else at AT is also busy so oh well.
Good work guys and I look forward to the "new CPU speed bump" article (or FX-57 for those not under NDAs).
Mark
PS. If ya'll have an opening for another web editor, you should hire #84 (ironchefmorimoto). I hear he can cook really well.
AtaStrumf - Wednesday, June 22, 2005 - link
Nicely corrected Derek, I think there are just a few typos left, like this one (**):Page 20
Power Consumption
We measured power consumption between the power supply and the wall. This multiplies essentially amplifies any differences in power draw because the powersupply is not 100% efficient. Ideally we would measure power draw of the card, but it is very difficult **determine** to determine the power draw from both the PCIe bus and the 12V molex connector.
AND a few double "Performances" in the title (Performance Performance) starting with page 10.
Nice card nVidia!!! I hope ATi isn't too far behind though. Crossfire --> cheap SLi ;-) I need a nice midrange product out by September when it'll be time to upgrade to a nice E6 stepping S939 A64 and something to take the place of my sweet old GF2 MX (I'm not kidding, I sold my 6600GT AGP, and now I'm waiting for the right time to move to PCIe).
IronChefMoto - Wednesday, June 22, 2005 - link
Amen -- you guys work hard on your articles. Keep up the great work. And don't f*cking bother the web editor. We...er...they don't get enough vacation as it is.IronChefMorimoto
(another web editor who needs a break)
Wesley Fink - Wednesday, June 22, 2005 - link
Derek was too modest to mention this in his comments, but I think you should know all the facts. Our Web Editor is on vacation and we are all doing our own HTML and editing for the next 10 days. In our usual process, the article goes from an Editor to the Web Editor who codes the article, checks the grammar, and checks for obvious content errors. Those steps are not in the loop right now.The next thing is NDA's and launches. We are always under the gun for launches, and lead times seem to get shorter and shorter. Derek was floating questions and graphs last night at 3 to 4 AM with an NDA of 9AM. Doing 21 pages of meaningful commentary in a short time frame, then having to code it in HTML (when someone else normally handles that task), is not as easy as it might appear.
I do know Derek as a very conscientious Editor and I would ask that you please give him, and the rest of us, a little slack this next week and a half. If you see errors please email the Editor of the article instead of making it the end of the world in these comments. I assure you we will fix what is wrong. That approach, given the short staff, would be a help to all of us. We all want to bring you the information and quality reviews you want and expect from AnandTech.
IronChefMoto - Wednesday, June 22, 2005 - link
#79 -- But why wouldn't it be a high quality article, mlittl3? I thought you told me that AT was infallible? Hmmm? ;-)Houdani - Wednesday, June 22, 2005 - link
Thanks for the refresh, Derek. I went back and took a peek at the revised graphs. I have a couple of comments on this article before you move on to the next project.>> When the Splinter Cell page was refreshed, the graph for 20x15x4 apparently disappeared.
>> When you removed the SLI's from the Guild War page, it looks like the 7800GTX changed from 50.5 to 55.1 (which is the score previously given to the 6800 Ultra SLI).
>> Several of the pages have scores for no AA benches listed first, while other pages have scores for the 4xAA listed first. While the titles for the graphs are correct, it's a little easier to read when you stay consistent in the ordering. This is a pretty minor nit-pick, though.
>> Thanks for updating the transparency images to include mouseover switches ... quite handy.
fishbits - Wednesday, June 22, 2005 - link
"They priced themselves into an extremely small market, and effectively made their 6800 series the second tier performance cards without really dropping the price on them. I'm not going to get one, but I do wonder how this will affect the company's bottom line."The 6800s were "priced into an extremely small market." How'd that line turn out? I don't imagine they've released this product with the intention of losing money overall. Why do you think retailers bought them? Because they know the cards won't sell and they're happy to take the loss? It's already been proven that people will pay for you to develop and sell a $300, wait $400, wait $500 video card. It's already been proven that people will pay a $100+ premium for cards that are incrementally better, not just a generation better. Sounds like this target is a natural, especially knowing it'll eventually fall into everyone else's purchasing ability.
Being able to say you have the bar-none best card out there by leaps and bounds is certainly worth something. Look at all the fanboys that are out there. Every week or month you're able to stay on top of the benches means you get more people who'll swear by your products no matter what for years to come. Everyone you can entice into buying your card who sees it as a good product will buy your brand in the future as a preference, all other options being equal. I could be wrong, but suspect Nvidia's going to make money off this just fine.
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"I am proud that our readership demands a quality above and beyond the norm, and I hope that that never changes. Everything in our power will be done to assure that events like this will not happen again."
See... that's why I'm a big fan of the site.
mlittl3 - Wednesday, June 22, 2005 - link
#78, I bet you didn't even read the article. How do you know it demonstrated editoral integrity?IronChefMoto - Wednesday, June 22, 2005 - link
#23 (mlittl3) still can't pronounce "Penske" and "terran" right, regardless of the great editorial integrity demonstrated by the AT team today. Thanks!