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Mt. Tiburon Testing Labs

2-4-$1—Nvidia's Dual-GPU AIB

Well, it’s not quite two for the price of one, but it’s close.

Long anticipated, since Nvidia showed its Quad solution in the big Dell tent at CES, the company has come out with a consumer version of the dual-GPU AIB.

And by installing two of these SLI-ready GeForce 7950 GX2 graphics AIBs into an nForce 4 SLI or 590/570 SLI-based motherboard, authorized system builders can build quad-SLI systems. So, quad is still not for consumers after all, sorry.

The GeForce 7950 GX2 offers two GPUs working simultaneously on a single card, which when added up gives you 48 pixel pipes and 1 GByte of 600-MHz GDDR3 memory on a single AIB, which Nvidia calculates to be 76.8 GBps of memory bandwidth, 38.4 GBps for each GPU.

Is it cheap?

The 7950 GX2 is available in etail for approximately $599 to $649, says the company (eVGA has one for $599). That means don’t rush down to Fry’s, BestBuy, or Dixon’s looking for one, but get online.

But let’s review. When the GF 7900 GTX came out it sold for as much as $750, and recently has been cut to as low as $520. So a dual G71 for $600 is pretty close to a two-for-the-price-of-one. What does that suggest, given that the clock speed of the GX2 is lower than that of the GTX?

Is it fast?

Nvidia’s GeForce 7950 GX2 in an Intel motherboard. (Source: Nvidia)

A single GeForce 7950 GX2 AIB will not be faster than two GeForce 7900 GTX AIBs in an SLI configuration because the clock speeds on the GeForce 7950 AIB are lower (500 MHz) than those on a GeForce 7900 GTX (650 MHz). However, the GeForce 7950 GX2 will outperform a single GeForce 7900 GTX. And, according to Nvidia, The higher-core clock speeds on the Nvidia GeForce 7950 GX2 give it a slight performance edge over the GeForce 7900 GT (~520 MHz) SLI in most benchmark tests.

And even though Nvidia officially won’t allow its partners to overclock the Geforce 7950 GX2 AIBs (due to heat and power supply issues), some of them will come up with the faster cards. For example, we don’t know if XFX made a deal with the big, green firm, but we’ve heard they are coming out with a 570-MHz version for just under $600. It will be interesting to see BFG and eVGA’s -reac-tion.

What else?

The AIB will provide hardware-accelerated H.264 support through Nvidia’s PureVideo technology, as well as High-bandwidth Digital Content Protection (HDCP)–capable (requires other compatible components that are also HDCP-capable).

It will support two display modes:

1. Performance mode is supported by using both GPUs to combine rendering power and drive a single display. This mode is recommended and provides the best performance.

2. Multiple monitor support is possible by using each GPU to drive a monitor.

There is an option in the control panel to switch between multi-monitor (single-GPU) and performance (multi-GPU combined rendering) modes.

As for motherboards, Nvidia says with a properly configured SBIOS, the 7950 GX2 will work with any PCI Express–compliant motherboard (see www.nvidia.com/GX2 for a list of compatible motherboards and SBIOS that have been tested by Nvidia). And to run this puppy you’ll need a minimum of 400W (with 12V current rating of 27A).

What do we think?

Block diagram of Nvidia’s GeForce 7950 GX2 AIB. (Source: Nvidia)

Asus made the first SLI AIB almost two years ago, so this isn’t a major technological leap. Nvidia has the 16-2x8 PCI switch from the quad development, so nothing new there. And, running two GPUs with eight PCIe lines each isn’t the max performance mode.

The price seems right, and it will provide a nice boost in performance for about the same price as the introduction of the 7900, and for folks who didn’t get one of them, here’s a second chance with more performance.

Not very likely Nvidia will let JPR’s Mt. Tiburon Testing Labs get their hands on one of these, so watch the web-zines for benchmark results.

ATI’s reaction

ATI has been late to the dual-GPU party every step of the way (even though they were among the first in 1999 with Rage Fury Maxx along woith 3Dfx Voodoo, and MetaByte’s PGP). And who couldn’t have predicted that Nvidia would come out with a dual-GPU AIB if they’d been to CES and seen or heard about the quad system Dell showed? It’s possible ATI will announce a dual-GPU AIB at Computex, or offer a dual x1900 combo at some low “special” price to compete with the 7950GX2, and they’ll most likely hammer at Nvidia about game support (ATI claiming to have 100% while Nvidia has, who knows?). AA and HDR will be other debating points, but the bottom line is Nvidia has one, ATI doesn’t.