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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mrdeez - Thursday, June 23, 2005 - link
Derek-Please post benches with resolutions that are commonly used or this article becomes a workstatin graphics card article and not one for gamers....I mean really 2046x3056 or whatever the hell...lol...#1 who games at that res??? While this card is powerful it should be mentioned that unless you use a res over 1600x12000 this card is unnecessary.......lol those were some ridculous resolutions though.......and again post some benches with 1280x1024 for us lcd'ers.....
Shinei - Thursday, June 23, 2005 - link
#95: Did you pay to read this article? I know I didn't...#94: I guess you missed the part where they said that all resolutions below 1600x1200 were essentially identical in performance? If you only play in 1024x768, why are you reading a review about a $600 video card--go buy a 6600GT instead.
jeffrey - Wednesday, June 22, 2005 - link
#83Has the staff at Anandtech not ever heard of "Vacation Coverage"?
The excuse of your Web Editor being on vacation is, in reality, an admission of improper planning.
A major hardware site that is dedicated to cutting-edge technology should have planned better. New high-end GPU launches happen by NVIDIA only about 2-3 times a year at most.
This was one of the HUGE launches of the year and it was messed-up becuase the team didn't feel it was important enough to get some help for the article. There was damage done to Anandtech today due to the article errors and due to the casual admission in post #83 about not caring to properly cover a "Super Bowl" type of product launch today.
Save your apologies to the message board, give them to Anand.
geekfool - Wednesday, June 22, 2005 - link
How about benchmarking some useful resolutions? This review was essentially useless.JarredWalton - Wednesday, June 22, 2005 - link
86 - Trust me, most of us other editors saw the article, and quite a few of us offered a helping hand. NDAs a a serious pain in the rear, though. Derek was busy pulling all nighters and functioning on limited sleep for several days, and just getting the article done is only half the battle. Getting the document and results into the document engine for a large article with a lot of graphs can take quite a while and is an error prone process.The commentary on the gaming benchmarks, for instance, was written in one order and posted in a different order. So please pardon the use of "this is another instance" or "once again" when we're talking about something for the first time. Anyway, I've got a spreadsheet of the benchmarks from early this morning, and other than non-functional SLI in a few games, the numbers appeared more or less correct. The text also didn't have as many typos. Crunch time and getting the final touches put on a major article isn't much fun.
Thankfully, I'm just the SFF/Guide man, so I'm rarely under NDA pressure. ;)
robp5p - Wednesday, June 22, 2005 - link
I would love to see someone start benchmarking in widescreen resolutions! 1920x1200 begs for a fast video card like this. As was pointed out, the only real benefits of the 7800 come at high resolutions, and many people buying high resolution monitors these days are getting widescreen LCD'sand btw, my 2405fpw is sitting in a box right next to me in the office, begging me to open it up before I get home...this thing will be fun to get home on the subway
patriot336 - Wednesday, June 22, 2005 - link
Where is the Monarch and Tiger love?TigerDirect http://www.tigerdirect.com/applications/searchtool...
Monarchcomputer http://www.monarchcomputer.com/Merchant2/merchant....
Both are 599.00$
BikeDude - Wednesday, June 22, 2005 - link
$600 for a card that only features single-link DVI outputs? Yeah right, pull the other one nVidia!--
Rune
ta2 - Wednesday, June 22, 2005 - link
As a player of eve-online, I can tell you that the game is entirely CPU dependent. On that matter, it will 100% any CPU you have. I mean ANY CPU. Also for the testing, you should use 1600x1200 max AA and AF and go into an area with many player ships on eve-online. I guarantee you will not get 60 FPS. Impractical and unscientific, but would still give better results than this review.TinyTeeth - Wednesday, June 22, 2005 - link
I am very impressed of the performance of the new chip. Nvidia seems to have fixed the problems SLI had during the 6800 generation.I am also pleased they have managed to deliver the cards so quickly. That also puts some pressure on ATI.