Benchmark Results: Low-Resolution 3D Performance
We've seen Ultrabooks with everything from 11.6" to 15.6" screens sporting resolutions between 1366x768 to 1920x1080. The problem is, as the native resolution goes up, so does the demand on your graphics processor. If all you have is HD Graphics 4000, playable performance is clearly possible in World of Warcraft at 1280x720. From there, you can choose whether you want to start increasing the game's resolution or its quality settings.
On the Sandy Bridge-based Ultrabook, you don't have as much flexibility. The game's already running at 50 FPS at 1280x720, leaving little room to jump to 1366x768 and add some of the quality features that'd make World of Warcraft look good. HD Graphics 3000 is simply too underpowered to guarantee playability on even very mainstream titles.
Not surprisingly, then, getting Battlefield 3 up to the point of fluidity is challenging indeed. At 800x600 using the Low quality preset, performance is unacceptable. It takes the Ivy Bridge architecture's HD Graphics 4000 engine to make this title even remotely viable. But when you're forced to dial down to such a low resolution and de-tune fidelity, it's time to find a different device for gaming.
Here's an interesting parting shot, though. There is some flexibility in Intel's Ultrabook definition. A system with a 14" display can have up to a 21 mm-tall Z-height, creating room for discrete graphics in the form factor. Gigabyte's U2442N, for example, qualifies as an Ultrabook, but comes equipped with Nvidia's GeForce GT 640M GPU. Faster configurations are going to command higher prices, naturally, but the U2442N might be worth consideration if gaming on a compact notebook is important to you.