New Intel ULV processors still a bad fit for MacBook Air

Intel finally took the wraps off its latest ULV mobile processors, aimed directly at the ultra-thin portable category. However, these new processors don’t present a clear upgrade path for the MacBook Air, leaving Apple with no good choices to make when it comes to refreshing its own ultra-thin laptop.

The most likely candidate from Intel’s latest Core i3, i5, and i7 mobile processors is the Core i5-540UM. Though its nominal speed rating is only 1.2GHz—much lower than the current MacBook Air’s LV Core 2 Duo at 1.86GHz or 2.13GHz—it can boost a single core up to 2GHz when conditions are right for Turbo Boost. Both cores are also hyperthreaded, so some performance advantages still exist on certain hyperthreading-friendly workloads even when running at a lower clockspeed.

However, there’s a slight potential performance disadvantage to going this route compared to the Core 2 Duos currently used. According to Intel’s specs for the 540UM, the processor comes with 3MB of cache, down from 6MB. This shrunken cache, when combined with hyperthreading, could be a recipe for some thrashing-induced slowdowns on more highly threaded workloads.

The cache issue is pretty trivial, though, compared to the choices Apple faces for graphics. Like the rest of Intel’s Arrandale-class mobile processors, these newest ULV models are still saddled with the fair-to-middling Intel HD integrated graphics processor stuck right on the processor package. This updated IGP is certainly an improvement over previous Intel offerings, but it won’t cut it as far as Apple is concerned—the IGP is roughly comparable to Apple’s last-generation NVIDIA 9400M integrated graphics, and isn’t compatible with OpenCL.

This is the tiny logic board that powers the MacBook Air. This 2008 version shows the small-outline Core 2 Duo (red) and the Intel controller with integrated graphics (green).

iFixit

Apple might consider trying to jam in a discrete mobile GPU and use its automatic graphics switching technology. However, the package for the CPU alone—along with the Intel IGP that Apple doesn’t even want—is twice the size of the small-outline Core 2 Duo used in current MacBook Air models. When the required small-form-factor chipset is included, that doesn’t leave room on the MacBook Air’s tiny logic board for a discrete GPU. And, even if Apple were to try and make space for all that, it would likely take up some of the precious space needed for battery capacity. A discrete GPU could negate a chunk of the power savings that the new processors offer, too, presenting Apple with a battery life double whammy.

Because Intel is still battling NVIDIA in court over whether it has the necessary license to make chipsets for Intel’s latest processors, Apple can’t pair these new Core i5 processors with the new NVIDIA 320M used in the new 13″ MacBook Pro and white MacBook. That means Apple would have to stick with Core 2 Duo processors, and it doesn’t appear that Intel is producing any newer small-outline versions. There would be a small performance improvement—especially paired with a likely RAM boost to 4GB—but not likely enough for current MacBook Air users to justify an upgrade.

Short of convincing Intel and NVIDIA to settle their differences, getting Intel to make a Core i5 processor without an IGP, and mating that to an NVIDIA 320M, Apple doesn’t really have any options to offer a compelling upgrade to the MacBook Air. Future Intel processors in the Sandy Bridge family will have the IGP further integrated by packaging it on the same die as the CPU itself; if Intel includes OpenCL support for those IGPs, Apple might have a viable upgrade path. Then again, Apple may not be willing to wait that long; it might just pull the plug on the MacBook Air entirely.