Stefan Mileschin

At the beginning of the year, Intel introduced the first 7W SDP Ivy Bridge parts in limited quantities with the promise that Haswell would bring even lower power options. We didn't see much OEM adoption of the 7W SDP IVB SKUs, but at the Haswell launch Intel made good on its promise to follow up with an even lower power version. The first Haswell Y-series parts carried a 6W SDP (and 11.5W TDP), and that value included the on-package PCH. Today Intel is announcing an even lower power version, once again in limited quantities. By the end of this year Haswell will be offered in a 4.5W SDP version (still 11.5W TDP).

I went through the SDP discussion earlier this year. But in short, Intel calculates TDP by looking at average power through a set of benchmarks that tend to include some of the worst case offenders on a desktop or notebook PC. The SDP thermal rating is specific only to Y-series parts and uses a lesser set of benchmarks, more appropriate for a thin tablet chassis, to determine average power. If you run Furmark on one of these parts and the OEM building the system does nothing to thermally manage the platform, it'll dissipate 11.5W. If you use it like a tablet, you should see 4.5W (or 6W depending on the SKU) as the average power dissipated. Realistically the 11.5W value can be boosted up to, but not sustained.

Moving from 6W SDP down to 4.5W SDP is a big deal because it enables something huge: fanless Haswell tablet designs. At 6W Intel recommends some sort of active cooling within the chassis, but at 4.5W it's possible to go completely fanless.

http://www.anandtech.com/show/7168/h...ater-this-year