Several weeks have passed since we first began our analysis of NVIDIA’s new generation of DirectX 10 video cards. Launched on November 8, 2006, the GeForce 8 series have become the leading performers out of all single GPU solutions, NVIDIA and ATI alike, available for retail. Today our analysis will center on multi-GPU configurations of the GTX and GTS models of the 8800 series. At the present moment, these are the only video cards available that support Microsoft DirectX 10.

This means that these two video cards, along with ATI’s concurrent solutions based on the as of yet unannounced Radeon R600 GPUs, will be able to take advantage of game titles based on DirectX 10 immediately when they are released. DirectX 10 based video games are expected to start appearing on the market in the next couple of months. Although developers are enthusiastic about the new features that will be made available in the new API, their enthusiasm is restricted due to the fact that DirectX 10 is Vista exclusive. Windows XP is currently the dominant OS on the market and it will take time for consumers to transition to Vista creating problems for developers. They could either risk losing sales by developing their game exclusively for DirectX 10, or they might opt upon sticking to the existing Windows XP user base and not supporting DX10.

For the past two years nearly all high-end solutions introduced by NVIDIA have supported SLI technology. This holds true for the 88000 GTS and GTX. In SLI, consumers are allowed to connect two 8800 video cards that are the same models. It is not required, however, to have the video cards be produced from the same manufacturer.

The following table displays the technical specifications for high-end video cards from NVIDIA and ATI running in single or multi-GPU mode:

In order to support DirectX 10, NVIDIA had to create a new architecture that was radically different compared to older architectures. Thus the G80 came into existence. One of the largest architectural changes is the use of unified shaders. Because of unified shaders, there are no longer any dedicated pixel and vertex shaders. Instead, unified shaders are able to work on physics, geometry, vertex, or pixel shading depending on the task at hand.

In the course of this article we have used all 4 new GeForce 8800 GTS and GTX cards. The manufacturers of these cards are Foxconn, Gainward, and XFX. As you will see, these cards are all designed similar to each other, save for a few aesthetical changes primarily on the cooling solution, since they are all based on the same NVIDIA reference design.

Our main focus in this article is to test the performance of the 8800 GTS and GTX have under SLI. We will use a combination of synthetic tests, gaming tests, and power consumption tests in order to give you a better understanding of what to expect using SLI with the G80 architecture.

The unique characteristic of the Foxconn 8800 GTS is the customized cooling solution. To make their card more attractive, the Taiwanese manufacturer placed LEDs between the plastic shell and the actual heatsink. Foxconn also chose upon a kind of space theme for their video card. We are not very sure, however, if we like it. Although it is unique, it just might not be what most people are looking for. Despite this, everyone has the right to their own opinion and ultimately, no matter what design this card has its still packing an 8800 GTS underneath.

The Foxconn package doesn’t come with a game; however, it does come with a couple of extra goodies. You get the standard DVI to VGA converter, a Molex to 6-pin power cable, an external video component cable, an S-Video connector, a Driver CD, a manual, and a system restore CD. Foxconn has also included a USB joypad with their video card which ends up looking like a mix between an Xbox 360 and PS2 controller.

Gainward’s Bliss GeForce 8800 GTX has a design that is very similar to the NVIDIA reference design with only a sticker on the cooling solution to set it apart. Historically, Gainward has been one of the most active partners of NVIDIA to overclock reference designs; however, because of NVIDIA’s ban on factory overclocking, this card runs at the standard rates of 575 MHz for the GPU and 1,800 MHz for the memory.

The video card comes packed with PowerDVD 6, Muvee’s autoProducer, and a voucher to download two titles from gainwardgamingzone.com. Although the idea behind the Gaming Zone is a good one, at the moment of this article’s writing there are only 8 available titles, none of them being particularly recent. Gainward also includes a video card manual, a DVI to VGA connector, and a TV out component cable.

Another famous manufacturer of factory overclocked cards is XFX and again, because of NVIDIA’s ban on factory overclocking, their card comes running at standard speeds. The main physical difference between the GTS and GTX models is that the GTS is slightly taller. Again, these solutions are only different from the NVIDIA reference design because of the stickers on the heatsink.

The accessories included with the card are identical between the two models. They comprise of a composite video dongle, an S-Video cable, two DVI to VGA adapters, a driver CD and a guide for installing the card into a computer case.

Power consumption is essential to keep in mind when buying a video card. Despite its importance, this aspect of a video card quite often gets overlooked. The 8800 series are very high performers and so we expect them to be more demanding in their consumption.

• Motherboard: Intel D975XBX2KR (chipset Intel 975X)
• Memory: Corsair CM2X1024 6400 (3-4-3-9) @ 800 MHz; 2x1 Gbyte
• hard disk: Western Digital WD1600JS - Serial ATA - 7.200 rpm, 160 Gbytes
• processor: Intel Core 2 Extreme X6800
• PSU Tagan TurboJet TG1100-U95 (1,100 Watts)

We conducted two power consumption tests in two different states. In the first state, idle, we had an empty desktop with only Windows XP running while in the second state, full load, we had Sciencemark 2.1 running at a resolution of 2560x1600.

Looking at our tests, we can immediately conclude that the GeForce 8800 GTX demands the most power out of all other video cards. Under SLI, the 8800 GTS and GTX yet again consume the most power, while the Radeon X1950XTX ends up taking in nearly 100 less watts.

Test Configuration

In order to properly benchmark the new generation of video cards, it is necessary to use a test platform that will not create a bottle neck for the video card thus limiting performance. For this reason, we chose to test using the Intel Core 2 Extreme X6800, which is currently Intel’s fastest dual-core solution available for retail. We chose this processor over the QX6700 because current video games do not take advantage of four cores. The Core 2 Extreme X6800 also has a clock of 2.93 GHz compared to one of 2.67 GHz for the QX6700.

The motherboard we chose to test with was the Socket LGA 775 Intel D975XBX2KR based on the Intel 975X chipset. For memory, we used 2 Gigabytes of Corsair XPS CM2X1024-6400C3 running at a frequency of 800 MHz at timings of to 3-4-3-9. The hard disk was a 160 Gigabyte Western Digital Caviar WD1600JS based on the SATA interface and running at an RPM of 7,200.

For mutli-GPU SLI tests, we used the EVGA nForce 680i which, as the name implies, is based on the NVIDIA nForce 680i chipset.
We used Windows XP SP2, updated with the latest fixes available in October of 2006, for all of our tests. The driver version used for NVIDIA cards was Forceware 96.94 while for ATI cards it was Catalyst 6.10. For the tests with GeForce 8800 GTX and GTS cards under SLI we have used Forceware 97.02.

our test system wtih a Dell 3007WFP

A fundamental item that is required in order to analyze high-end video cards is a display that supports high resolutions. It would not make sense for a person to buy some of the most powerful video cards on the market only to use it for a low resolution display. Our choice fell upon two displays that natively support the resolution of 2560x1600 and are currently available for retail. We chose to use the Dell 3007WFP widescreen, which measures in at 30 inches.

In order to test these high-end video cards to their fullest, the resolutions of our benchmarks in this article do not get any lower than 1600x1200. We also made sure that under no circumstances anisotropic filter was set at anything lower than 16x.

For NVIDIA cards, we compared the GeForce 8800 GTX against the GeForce 7950 GX2 and GeForce 7900 GTX. The GeForce 7950 GX2 was chosen because it is one of the fastest single slot solutions from NVIDIA while the 7900 GTX was chosen because it is the main flagship for the previous generation of NVIDIA products. For ATI solutions, the main contender was the Radeon X1950XTX which was selected because it is the only contender to the 8800 GTX until R600 based video cards are released in early 2007. The 7950 GX2 board we used for testing was from XFX and was significantly overclocked to 570 MHz GPU and 1,550 MHz memory.

In order to provide additional information regarding the performance of these video cards when running on a 19inch widescreen LCD monitor with a maximum resolution of 1280x1024, we also ran some tests at this resolution.

Combining two video cards with SLI allows for large leaps in performance in 3D Mark 2006 fill rate tests. In fill rate multi-texturing tests the results of the SLI 8800 GTX setup are actually double that of a single card meaning 100% scalability going from one to two cards.

We get similar results in the pixel and vertex shader tests. The use of SLI technology doubles performance, as can be seen with the GeForce 7900 GTX.

In the Perlin Noise benchmark, which was initially released in the 2005 version of 3D Mark, the SLI setups again are able to reach almost perfect scalability.

Shadermark 2.1 shows an interesting view of the tested cards’ performances. The GeForce 8800 architectures display the highest overall performance. Oddly, the ATI solutions at times show lesser performances with two cards compared to a single card configuration. This is most evident at 19 on the graph.

For the Splinter Cell Chaos Theory tests, our game was updated to version 1.05. The tests were executed using the Ubisoft Lighthouse demo. The test resolutions were at 1600x1200 and 2080x1536. Anisotropic filtering was always set at 16x. Anti-aliasing was set at 4x only in the first test while in the second test we had High Dynamic Range enabled.

The 8800 GTX SLI setup shows its true value under the HDR test. The GeForce 7900 GTX SLI system has performance that is comparable to 8800 GTX SLI in the first test, however, with HDR enabled the 7900 GTX takes a major dip in FPS. The 8800 GTX, on the other hand, is able to actually increase its performance while the 8800 GTS’ performance remains relatively the same.

For this analysis, we made sure that our copy of Serious Sam 2 was updated to the most recent patch, version 2.070. We used the Branchester scene in the game and benchmarked using Hocbench. The testing resolutions were 1600x1200 and 2048x1536. In the first test we had anti-aliasing set at 4x while in the second test we had HDR enabled. Both tests had anisotropic filtering at 16x.

In Serious Sam 2 the 8800 GTX GPUs are mainly CPU limited. This is obvious because as we raise the resolutions of the benchmarks, the frame rate takes a minimal negative impact. The quality of the new G80 architecture is displayed by the fact that a single 8800 GTX video card is able to outperform both 7900 GTX SLI and Radeon X1950XTX Crossfire setups.

F.E.A.R. was one of the most popular games used to benchmark video cards from previous generations. Because of its widespread use, it is an excellent program to compare results to previous architectures. F.E.A.R is a game greatly stresses the video subsystem.

The stress placed on the GPU can be further increased by enabling soft shadows. In previous generations of video cards, enabling soft shadows had a very large negative impact on performance. With the G80 released, we just couldn’t resist trying the game with soft shadows enabled. The main purpose of soft shadows is to add a slight haze to the edge of shadows in order to make them seem more realistic.

The version of F.E.A.R. we used for the tests was 1. 08. We used resolutions of 1600x1200, 1920x1200 and 2560x1600. In the first two tests we used AA 4x and AF 16x while in the last test we used only soft shadows

The GeForce 8800 GTX SLI system outdoes every other video card setup. The GeForce 8800 GTS, on the other hand, performs on par with a single GeForce 8800 GTX card. Both are able to perform better than two 7600 GT cards in SLI. The GTS system had quite high FPS until we set the resolution at 2560x1600 after which it drastically fell to 34 FPS.

The GeForce 8800 SLI setups have the highest minimum frames per second. As can be seen, the only time performance for the 8800 systems dipped into the unplayable range was at 2560x1600.

With Soft Shadows enabled the margin of advantage for the 8800 series increases by a very large amount. As we previously mentioned, Soft Shadows didn’t work very well with previous generations of video cards, however, it seems that that problem has been rectified with the introduction of NVIDIA’s new architecture. In this case, a single GeForce 8800 GTX is able to outdo two GeForce 7900 GT cards under SLI and is also faster than Radeon X1950 XTX. A single GeForce 8800 GTS card is also able to perform faster than the Radeon X1950XTX Crossfire setup.

Episode 1 is Valve’s latest expansion to Half-Life 2 which was primarily distributed through Steam. Historically a test that usually works pretty well with the Radeon architecture, this will be an excellent test to see the value of a 8800 GTX SLI system compared to Radeon X1950XTX Crossfire. We tested with the game running at resolutions of 1920x1200 and 2560x1600 pixels. For the first test we used 4xAA and 16xAF, in the second test we used HDR with 16x AF, and in the last test, Lost Coast, we used 4xAA and 16x AF.

In the first test, the GeForce 8800 GTX SLI system is faster than all other solutions by a long shot. The GeForce 8800 GTS SLI system also manages to make it over 100 FPS at 2560x1600 and has an overall performance of second place. With HDR enabled, the X1950XTX Crossfire solution performs quite well, outdoing the 8800 GTS SLI in order to gain second in overall performance. Despite this, the 8800 GTX SLI system is still the fastest.

Two GeForce 8800 GTS cards under SLI end up having performance comparable to the Radeon X1950XTX Crossfire. Ultimately, though, the Radeon X1950XTX Crossfire system is faster than the 8800 GTS SLI system. The GeForce 8800 GTX SLI still is the fastest solution and holds a large margin of advantage over the Radeon X1950XTX Crossfire solution.

Prey, which was released a few months back, is a game that is based on a modified version of the Doom 3 engine. To test performance in this game, we used a retail copy and tested using the tool Hocbench using the demo hwzone. Our chosen testing resolutions were 1600x1200 and 2560x1600 with anti-aliasing at 4x and anisotropic filtering at 16x.

In Prey, going from 1600x1200 to 2560x1600 reduces performance by quite a lot. A single GeForce 8800 GTX turns out to be faster than two GeForce 7900 GTX cards under SLI.

For Call of Duty 2, the GeForce 8800 GTX performs the fastest having a large lead over the GeForce 8800 GTS and all other solutions. For the rolling demo of X3 Reunion, the GeForce 8800 GTX SLI system’s lead is significantly cut down compared to Call of Duty 2. At 1920x1200 pixels, the 8800 GTX SLI is actually slightly slower than the Radeon X1950XTX Crossfire, however, the 8800GTX has better scalability and performs faster at 2560x1600.

Since 19inch LCD displays are still quite popular and the resolution of 1280x1024 is still widely used among PC gamers, we included a number of tests just to give a general idea of how these cards perform at this resolution. None of these tests have multiple cards and all were run with a single video card.

For consumers who have a budget with quite a large amount of headroom, two GeForce 8800 GTX video cards combined using SLI technology makes the fastest gaming solution on the market. Two of these video cards, though, don’t come very cheap. The average price for a single card is around $650 so two of these cards weigh in at around $1300 USD. For our UK readers, this is around 665.91 pounds. Availability for 8800 GTX video cards, however, are still low and so it might prove difficult getting one card let alone two.

Scalability for the 8800 series going from one video card to two was impressive. The GeForce 8000 series currently have excellent DirectX 9 performance and as their architectures are designed for DirectX 10 they will be able to take immediate advantage of DirectX 10 games when they are released. Here is a table that summarizes the scalability of the tested video cards.

Percent % increase going from one card to two

For the price of a GeForce 8800GTX SLI system, it is important to realize that $1300 USD will not be your final cost. If you are constructing a system from scratch, you would still have to factor in the price of the motherboard and, in order to not limit GPU performance with the CPU, factor in the price of a high-end CPU. You would also have to purchase an adequate power supply to power this system. It wouldn’t make sense to spend so much money on a powerful system just to run games at low resolutions, and so we naturally assume you will be buying a display that supports extremely high resolutions. For our testing, we used a Dell 3007WFP, a flat panel LCD monitor which runs in the price range of around $1,000. Add up the price of all of these components, and the final cost comes out to be quite hefty.

There isn’t much else to say about SLI with the GeForce 8800 series. As our tests proved, the GeForce 8800 GTX SLI is currently the fastest video card solution on the market. SLI secured the 8800GTX’s performance lead over other video cards and, as our scalability table above proves, greatly increased performance. Again, the two main considerations that might prevent people from being able to get this type of system for this holiday season is availability and price, price being the larger factor of the two.