NVIDIA's Optimus Technology - Best of Both Worlds
NVIDIA was the first to implement switchable graphics, where a notebook has both integrated and discrete graphics and one can switch between the two as desired. Taking this step further, the company has announced its Optimus technology, where the switching is done automatically. We check out this new feature that will soon be heading your way.
The Flaws of Switchable Graphics
Depending on where you're coming from, Optimus, the new notebook technology
that NVIDIA has announced today, is either a major improvement or a major patch. To provide some background, NVIDIA was the first to introduce the idea of switchable graphics (or Hybrid Graphics as NVIDIA calls it) on notebooks with both integrated and discrete graphics processors (GPU).
Users are given the choice of toggling between the two. For instance, if you're playing a 3D game, you would prefer the NVIDIA discrete solution for better performance. For less intensive tasks like browsing the web, you could change back to the integrated (usually Intel) graphics for a longer battery life.
On paper, this ability to switch on-the-fly sounded like the best of both worlds. Unfortunately, the reality, as NVIDIA found in a survey, was that only 1% of users actually used this feature. The vast majority simply didn't know how to use it properly or was uncertain on how it worked.
There were a few issues with current switchable graphics. Since it involved switching between two separate graphics subsystems within the notebook using what's called a hardware multiplexer, there was a discernible lag of between five and ten seconds. This was actually an improvement over the earliest implementations, where one has to reboot the notebook to enable the switch. Besides the lag during transition, the screen would also flicker, leading users to fear an impending system crash.
The interface too was responsible for the ignorance of switchable graphics as the option to switch was buried in the Windows power plan menu. Additionally, you have to close all open applications before the transition could occur. These main drawbacks of the state of switchable graphics prompted NVIDIA to improve on this technology, culminating in Optimus today.
What is Optimus Technology?
What Optimus does is to make the switch between integrated and discrete completely transparent to the user. The process is automatic, with the software
deciding which graphics processor will handle the application. It is also fast, with NVIDIA claiming that powering on the discrete GPU takes less than half a second. When it's turned off, the discrete GPU will not draw any power, so one gets the same battery life as if the notebook only had integrated graphics.
According to NVIDIA, we have to think of Optimus profiles like antivirus definitions, which will be pushed to users through the internet as and when new applications or games are released which may require the profiles.
How will Optimus know which graphics processor to use for each application? It depends on the application and process call type, namely, CUDA calls, DirectX (DX) calls and DXVA calls. Obviously, it's straightforward for CUDA and DXVA calls, as they will immediately evoke the discrete graphics. For DX calls, it can be more difficult to tell if a certain game requires the full performance of the discrete GPU.
Hence for these cases, the software will depend on application profiles supplied by NVIDIA. This will be pushed out to users via the internet, with NVIDIA comparing them to antivirus definition updates. Of course, users can choose to tweak the profiles manually, as we shall try later during our hands-on with the ASUS UL50VF - one of the first notebooks to adopt the NVIDIA Optimus technology.
As for what happens underneath, the new Optimus design reduces the cost of producing switchable graphics by removing the additional hardware required, like the multiplexer that does the actual display switching between the integrated and discrete GPU. In the improved version, the display output only goes through the integrated graphics, regardless of which graphics engine (discrete or integrated) actually did the work. So if an application has been flagged to use the discrete graphics, the resultant data generated is sent directly to the frame buffer of the integrated graphics, which will then output it through the proper display interface like LVDS to the notebook screen or other output options to external screens.
What's different from the older switchable graphics is that the discrete graphics use the IGP's display controller to show its rendered results, sort of like a pass-through.
This however requires some new hardware. Basically, a hardware feature that NVIDIA calls the Optimus Copy Engine does this data transfer between the frame buffer of the discrete GPU and the integrated GPU (which generally uses a reserved portion of system memory) via the PCIe Express bus. This fast transfer is what makes the seamless switching of the Optimus feature possible, by removing the need for the multiplexer and its associated lag.
Testing the Optimus
To find out all about the Optimus, NVIDIA sent us an ASUS UL50VF, a notebook using a Core 2 Duo U7300 CULV processor with 4GB of system memory. Windows 7, with its support for multiple graphics drivers, correctly identifies two different GPUs, the integrated Mobile Intel 4-series chipset and the NVIDIA GeForce G210M, along with their relevant driver control panels.
The notebook also comes with an NVIDIA test tool, a small status indicator to show if the NVIDIA GPU is turned on or off. This test tool will not be found in retail Optimus notebooks because the experience is about seamless, transparent switching. However, we see the value of having at least a status indicator to show what GPU is actually working.
We tried the various pre-installed programs on the review unit, from 3DMark06 to Badaboom. Optimus worked as it should, turning on the discrete GPU for these applications. The discrete GPU was also triggered when we went to check out some YouTube videos and it didn't matter whether the video was HD or not.
Next, we tried installing another program on our own, Media Player Classic. When we tried to play a HD video clip using Media Player Classic however, the NVIDIA GPU failed to run. It appeared that this media player was not listed in NVIDIA's profiles. So, we went to the NVIDIA Control Panel to change the settings manually.
One can always create your own profiles to determine whether the integrated or the discrete graphics does the processing for each application.
In fact, you can even add the choice of integrated or discrete to your context menu by enabling it in the NVIDIA Control Panel. After which you can simply right-click an application and decide which GPU to run it with, integrated or discrete.
There are two ways of doing it, either by creating a new profile in the Control Panel or by enabling the contextual menu option. By doing so, you can right-click the application icon and choose whether to run it with the discrete or integrated GPU. Both methods worked as intended and we got the discrete GPU to run with Media Player Classic. From the user point of view, there's indeed little indication which GPU is doing the work and without the test tool, we would have no idea either, except that HD playback was very smooth. It makes us inclined to favor the presence of a status icon at the very least.
At the bottom right corner is the Test tool provided by NVIDIA to show whether the discrete GPU is on or off. This is for evaluation purposes and it's not found in retail versions since the switching is supposed to be transparent and automatic.
The Optimus technology will support notebooks with the Arrandale or Core 2 Duo processors and even Pine Trail platforms (the latest netbook platform using the new Pineview processor and I/O hub). On the GPU side, NVIDIA's current GeForce 200M and 300M products will support it, along with its next-gen Ion and GeForce mobile products.
NVIDIA states that it has garnered more than 50 design wins among notebook vendors for this technology, with the majority available this coming summer. Launch partner ASUS has already announced five Optimus-enabled notebooks, out of which two models are available in Singapore in mid-March.
It's early days for this technology but an intelligent and automatic switching technology that appropriately brings the best of both performance and battery life from a notebook is certainly extremely desirable. NVIDIA has not ruled out implementing this on the desktop but at the moment, the mobile arena is its main concern. If it's a runaway success, who knows what the future holds?
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