AMD arguably has the better reputation (lately, at least) for maintaining a given socket interface and carrying it over as far as possible to support its latest processors. But Clarkdale was a win for Intel in that it employed the LGA 1156 interface introduced alongside Lynnfield (even if existing P55-based motherboards couldn’t take advantage of Clarkdale’s on-package graphics core).
Gulftown is made even more compelling by virtue of the fact that it drops into the same LGA 1366-based platforms introduced next to Bloomfield. This means coming in under the same 130W TDP.
At idle, the Core i7-980X actually uses a bit more power than Core i7-975 Extreme (likely a result of the slightly higher idle voltage reported by CPU-Z). But under load, the 32nm Gulftown chip goes lighter on power consumption. We wouldn’t advocate the Core i7-980X as a power-saving play, but it is amazing to see how 32nm manufacturing allows such a complex hexa-core processor to pull less juice from the wall than last-generation’s 45nm quad-core.
That observation aside, AMD’s Phenom II X4 965 scales back to 800 MHz at idle, hitting a low 94W system idle. But it’s not the lowest consumer under load—that honor (at least in the context of these five CPUs) goes to the Core i5-750, which is rated for up to 95W itself, but also benefits from a more efficient two-chip platform consisting of processor and PCH. The other contenders all lean on a processor, northbridge, and southbridge.