A Crash Course on Nvidia Hybrid SLI

Sometime in May or June this summer a new graphics solution will be available on store shelves, and it's called Hybrid SLI. Here's our crash course on the newest version of Nvidia's scalable link interface that will combine multiple graphics processors in a brand-new way. Integrated vs. Discrete Graphics Solutions Before we begin, I’ll explain the difference between integrated and discrete graphics. Integrated got the name “integrated” for a reason: The chipset brings the graphics and other system elements together. More on that in a bit. Integrated graphics are typically less powerful, and that’s because the processor uses your system RAM instead of its own video RAM. Integrated graphics are fine for everyday tasks like word processing, but not for heavy video processing or gaming. Discrete graphics processing units have their own RAM, and some can tap into system RAM when they need to. While a discrete GPU may save on system resources by providing its own RAM, it sucks more electricity. That’s why gaming laptops have such a horrid battery life. When we say "discrete," think "dedicated" graphics. What is Hybrid SLI? Currently, an SLI-enabled computer takes two discrete graphics processing units (GPUs) and lets them work together. It’s like saying “two heads are better than one,” except in the case of SLI, two powerful discrete graphics cards are more powerful than just one (of the same or lesser value). Hybrid SLI will take two graphics processing units (an mGPU chipset and a dGPU) and force them to work together as well, except instead of taking two discrete GPUs, Hybrid SLI will combine the power of both an integrated motherboard graphics processing chipset (mGPU) and a discrete graphics processing unit (dGPU). To explain this better, like other chipsets, the mGPU acts as the glue inside a system; it brings elements like the GPU, hard drive interface, USB drives, and wireless capabilities together. The mGPU works with both your CPU and your system RAM, and your dGPU will work with the mGPU. When not in use, the dGPU will power down, saving valuable battery life.

What kind of benefits does Hybrid SLI offer and how does it work? Instead of having two high-powered GPUs always working together to provide you the power needed for high-performance gaming, Hybrid SLI will let you choose either high performance or low power. That means you’ll be able to save on battery life when you don’t need both GPUs running at full power. In low-power mode, your mGPU will be the only GPU running, but when you need to pump out some serious juice for gaming, both GPUs will be active and working together, to put out the power needed for more graphics-heavy tasks. When both are running together, you’re experiencing what Nvidia calls its “GeForce Boost” feature of Hybrid SLI. The boost increases graphics processing power in the range of 40 to 80 percent from simply running off of only integrated graphics. Users will see higher frame rates in games, and applications that use graphics processing will perform better. When your notebook is unplugged, it will automatically default to the low-power mGPU mode, and the dGPU will power itself down to save power. What about the enthusiast gamers that want two discrete cards running in SLI? Power-hungry user, eh? We feel you. Some systems will ship with both Hybrid SLI and SLI. That means that there will be an mGPU, and two discrete GPUs. When the system is running in a “power-hungry-like-the-wolf" mode, all of the GPUs will be shredding frame rates (and the neighborhood power block) together. The benefit to this approach is that gaming laptops will finally be able to power down to an mGPU power-saving mode without leaving the power-hogging discrete GPUs on all of the time. In other words, you’ll finally be able to tote that big LAN party machine on the plane and actually use it for routine tasks while experiencing an extended battery life. Are there any downsides to Hybrid SLI? It all depends on how much you like Vista. Hybrid SLI will only run under Vista, so if you’re a Windows XP fan, like many of us are, then you won’t be able to reap any of the benefits. On the other hand, it’s going to be harder and harder to buy a notebook without Vista anyway. What notebooks will have Hybrid SLI? Nvidia hasn’t specified which manufacturers will use its Hybrid SLI technology, but it did confirm that the current top-ten notebook makers would be releasing something in the summer timeframe. This time around, however, Hybrid SLI won’t be limited to the larger desktop-replacement type computers. Nvidia told us it will also be available in 14-inch notebooks. Who will reap the largest benefit of Hybrid SLI? Nvidia argues that everyone will see benefits from Hybrid SLI. We believe that everyone from media-hungry users, to casual gamers, to workers that need a little extra oomph for faster video encoding and photo editing will benefit. NVIDIA also told us that applications using its CUDA development kit would be available at the time of the Hybrid SLI launch and that the applications would take advantage of its capabilities. Movie watchers will also see an increase in playback quality. Anyone who hates their notebook's battery life due to discrete graphics will also see an increase in battery-life performance once discrete graphics are turned off. In other words, your grandmother probably won’t see a change in her surfing experience. On the other hand, the nice thing about Hybrid SLI is that it will mostly run in the background unless you decide to tweak the power settings yourself, so it won’t take a computer scientist to understand what’s going on either. How much will Hybrid SLI cost and when will we see it? Today there are different options in graphics processors. We have integrated, discrete, and two cards running together (Nvidia calls this SLI, ATI calls it CrossFire). Nvidia told us that we’d see mGPU standalone options from Nvidia, mGPU/Hybrid SLI options from Nvidia, and Hybrid SLI/SLI Enthusiast options available. The pricing of each product will likely increase in that order, too, depending on the models chosen. When will Hybrid SLI–equipped notebooks hit store shelves, and how can I tell which models have it? Nvidia told us we’d see notebooks with Hybrid SLI sometime this summer. It wasn’t sure what each system label will look like, although the company expects some sort of sticker or text-treatment explaining that “Hybrid SLI” technology is included.