Intel's Haswell for Ultrabooks: Power Savings Aplenty

By Wesley Fenlon

Four of Intel's new ultra low voltage i5 and i7 chips come with faster HD 5000 GPUs, and each and every one is more power efficient than last year's Ivy Bridge.

Intel's Haswell CPUs are coming. On the desktop side, we've already dug into what that means--a new socket, lower power draw, and some nice performance improvements for heavy users. But what about Ultrabooks? On Monday Intel released details on the U-Series processors designed for those lightweight laptops Intel is so fond of. These dual-core, 15 watt TDP chips will be powering Ultrabooks later this year. So what do we have to look forward to? You may sense a theme, but lower power usage is a big draw for this mobile year's chips.

Ars Technica covered the details of the Haswell mobile processors, pointing out that the ultra low voltage chips this generation are even more power efficient than they first appear. The Ivy Bridge ULV chips ran with a 17 watt TDP, but that figure didn't include the chipset, which added another three watts. Ars writes "The 15 watt TDP figure for the U-series Haswell chips includes the chipset, making for a 25 percent combined reduction in TDP. Combined with the "active idle" power state, which allows Haswell laptops do more when idle and transition between active and idle states more quickly, Haswell has the potential to enable significantly better battery life for general-usage workloads."

Since the chipset is integrated into the CPU this time around, it frees up a little space for other Ultrabook components. Specs-wise, the U-series CPUs don't offer much surprising. They're dual-core processors with Hyperthreading and clock between 2.9GHz and 2.3GHz, between the high-end i7 and low-end i5. Two bottom of the barrel i3 processors are stuck around 1.8GHz and drop Intel's Turbo Boost which enables even higher clock speeds. The i3s and i5s feature 3MB L3 cache, while the i7s bump that up a bit to 4MB.

The big difference lies in the GPUs, which we wrote about in early May. Here's a refresher: Intel estimates its new HD Graphics 5000 will deliver 1.5 times the graphics performance of last year's GPUs. Intel's top-of-the-line integrated graphics, the Iris 5100, will offer about double the performance of last year's GPUs, but is too power hungry for these ULV processors. You'll only see it in bigger laptops.

The two fastest i7 and i5 processors in the U-Processor line will run on Graphics 5000, while the lower entries in each category will stick with Graphics 4400, which are lower-power GPUs. Ars Technica writes that the faster GPUs (coupled with lower power draw) could give Ultrabooks a big competitive edge compared to larger laptops--they're still thin and light, but now they have some real graphics power. CPU performance may feel identical to last year's Ivy Bridge laptops, however:

"Those more powerful HD 5000 GPUs come with a cost, however, namely in lower base CPU clock speeds for the CPUs that include them," Ars writes. "The architectural improvements Haswell brings to the table should close that gap most of the time (as should the higher Turbo speeds, at least for short bursts of activity), but the maximum CPU performance of the Haswell-based Ultrabook CPUs with the HD 5000 may actually be level with or perhaps a bit lower than the peak performance of the analogous Ivy Bridge parts."

1.5 times the GPU performance for roughly equal CPU speed sounds like a deal to us, especially if Intel's claims of dramatically increases battery life come true. Expect to see Haswell chips in Ultrabooks popping up later this year, and likely in Apple's new MacBooks.