After the NVIDIA Optimus teaser was posted in early January, there was some speculation about what it was, but we now have first-hand information: NVIDIA Optimus is an architecture for multi-GPU computers (typically integrated + discrete) that allows the operating system to seamlessly switch between integrated and discrete graphics. The goal is to use the most appropriate graphics processor at any given time in order to minimize power consumption or maximize performance.
I’ve seen it in action, and I can tell you that it is leaps and bounds better than what is out there today. Typically, today’s computers require several steps in order to switch from one GPU to another. It’s not intuitive and most users don’t even bother doing it because it’s a hassle.
Optimus uses “app profiles” to determine when an application requires more GPU horsepower and switches to the faster, but more power-hungry, discrete GPU. Upon exit, the computer switches back to the integrated GPU that uses less power. It was demonstrated to me with a combination of Intel integrated graphics and NVIDIA discrete GPU, but it could work with other combinations as well. For apps without a profile, well you might have to do it the old way, but I expect most popular apps to “just work”.
NVIDIA has been working on this for a while, but the company had to add extra hardware and change its drivers to build a completely seamless switch mechanism. If you are curious, and in a nutshell, the integrated graphics (IGP) is used as a video controller and is always connected to the screen: that prevents the screen flickering during the “switch”. Then, a common video memory zone is used by both the IGP and the discrete graphics processor (GPU) to store the final frame. Extra-hardware (a DMA array) has been added to the GPU to copy the frame rendered by the GPU to the common video memory. New drivers are required to make all this work, and your application needs to have a profile – I expect NVIDIA to update the profiles fairly quickly. Note that there is no need to update the video driver to get new profiles. It works like an anti-virus update.
The details are interesting, but most folks shouldn’t even have to care about the inner workings: the great news is that it just works. It’s funny because that’s the way it should be, and that’s how NVIDIA puts it: if you’re driving a Hybrid car, you should not worry about which engine is currently moving the vehicle forward. That’s what Optimus is.
Optimus will be available on new ASUS laptops like the N82Jv, U30Jc, N71Jv, N61Jv. More laptops from various manufacturers will follow.