GeForce 9800 GX2 Quad SLI Performance Preview

Last week we examined the performance of NVIDIA’s dual-GPU GeForce 9800 GX2 graphics card. In the article we found that the GeForce 9800 GX2 is easily the fastest single graphics card on the market, with the GeForce 9800 GX2 often running 25-30% faster than NVIDIA’s previous flagship, the GeForce 8800 Ultra.

The only graphics setup we tested that was faster than the GeForce 9800 GX2 were a pair of GeForce 8800 GTS 512MB cards running in SLI. The GeForce 8800 GTS 512MB runs at slightly higher speeds than the 9800 GX2 – 670MHz core/1625MHz stream processors versus the 9800 GX2’s 600MHz core/1500MHz shaders – which accounts for the GTS’ superior showing in our benchmarks. We concluded by saying that the GeForce 8800 GTS 512MB SLI setup was a better value thanks to aggressive street prices for the GeForce 8800 GTS 512MB SLI and NVIDIA’s $600+ MSRP for the GeForce 9800 GX2. After all, why spend more money on the GeForce 9800 GX2 when GeForce 8800 GTS 512MB cards can be found for half the price?

The answer to that question varies; if you don’t currently own an SLI motherboard, running a pair of GeForce 8800 GTS 512MB cards in SLI mode isn’t an option for you. For the über high-end gamer that craves the absolute highest performance and will pay anything to obtain it, the GeForce 9800 GX2 supports one unique feature that puts it in a class of its own: Quad SLI.

The theory behind Quad SLI is the same as conventional 2-Way SLI. By combining two GeForce 9800 GX2 cards together, performance improves dramatically. Performance won’t magically double (due to a host of factors such as driver overhead, game engine limitations/optimization and the speed of your CPU), but performance improvements of 50% or more are possible under some conditions. The actual performance boost you’ll see from Quad SLI will vary based on the game being tested and the settings used. Obviously the harder you push the graphics card, the higher the benefit you should see from running Quad SLI versus a single GeForce 9800 GX2. This means gaming at resolutions of 1920x1200 or higher (with Crysis being the obvious exception), with the AA/AF and game settings cranked all the way up.

If you recall NVIDIA’s previous Quad SLI card, the GeForce 7950 GX2, you’ll no doubt remember the issues NVIDIA encountered getting all four GPUs in Quad to scale properly. Because of limitations in DX9 Windows XP, 7950 GX2 Quad SLI cards couldn’t run 4-Way AFR in D3D titles, instead they had to rely on AFR of SFR or 2-Way SLI modes. Fortunately this issue has been resolved in Windows Vista, allowing them to finally render up to four frames simultaneously with the 9800 GX2 cards running Quad.

Powering a GeForce 9800 GX2 Quad SLI system

With a single GeForce 9800 GX2 card consuming nearly 200W of power at peak load, powering two cards is obviously going to require a pretty beefy power supply. NVIDIA’s recommended guidelines for the GeForce 9800 GX2 call for an 850W power supply at the minimum, while a 1-kilowatt (1,000W) PSU is recommended. The PSU must also have two 6-pin and two 8-pin PCIe power connectors. Unfortunately there’s no getting around this requirement. NVIDIA will provide a full list of certified components on slizone.com.

In our testing, our 3.2GHz QX9770 testbed with a 1.1-kw PSU and two 9800 GX2 cards idled at 302W, and consumed an astounding 497W at load.

Fortunately the GeForce 9800 GX2 supports NVIDIA’s HybridPower technology, allowing both GeForce 9800 GX2 cards to power completely down during 2D operations, so once HybridPower-compatible motherboards are available, that idle power consumption figure should drop substantially.

Testing the 9800 GX2

To test the performance of the GeForce 9800 GX2 Quad, EVGA sent over a pair of their e-GeForce 9800 GX2 cards. These boards are based entirely on NVIDIA’s reference design, following NVIDIA’s specs to the letter. For now at least, NVIDIA is locking down all their board partners for the 9800 GX2, so there will be no differentiation among the various 9800 GX2 cards on the market, they’re all basically identical to one another.

Instead, other intangibles such as the game bundle, price, and warranty/tech support will be important. The e-GeForce 9800 GX2 carries an MSRP of $599.99, pricing it in line with NVIDIA’s official pricing, and while the card doesn’t come with a game bundle, EVGA is well respected for their lifetime warranty policy and excellent tech support both online and over the phone, where the company maintains 24/7 toll-free support for North American users. EVGA has also increased their Step Up program from 90 days to 120 days exclusively for the GeForce 9800 GX2. This gives those of you who purchased EVGA cards four months ago the opportunity to upgrade your current card to an e-GeForce 9800 GX2 for the full purchase price you paid back in 2007.