Intel has announced that a 4th generation Core processor with an SDP of 4.5 watts will be made available in the second half of 2013. In addition to the headlining 4.5 watt processor 6 watt versions will also be produced. The new 4.5 watt processors will allow device manufacturers to introduce the first tablets and 2-in-1 devices sans fans, according to Intel.
The full news release penned by Intel is very short, I've embedded it below:
Less than a year after announcing its intention to deliver Intel Core processors operating at less than 10 watts and two months after delivering 4th generation Core processors operating at 6 watts scenario design power (SDP), Intel has confirmed a new 4th generation Core processor will be available operating at as low as 4.5 watts SDP, in addition to the 6 watt versions. These chips, to be available in the second half of 2013, will allow device manufacturers to produce the first fanless 2-in-1 and tablet designs based on the Core processor.
The idea is that having these new 4.5 watt processors will open up a lot of size reduction possibilities to device designers, they should enable the production of thinner and lighter Intel Core devices than any produced previously.
However don't get your hopes up too high, for a slew of Intel Core powered fanless tablets arriving any time soon. AnandTech reports that these new processors will be available in "limited volumes" so may well be as scarce as devices built using the previous generation 7W SDP Ivy Bridge processor. The site also notes that the rest of the components making up a Haswell based device aren't yet as small as the ARM equivalents so ARM device rivalling svelte designs aren't just going to appear overnight. Also looking at Intel 4th gen processor efficiency, a Haswell ULT tablet processor used a lot of juice during video playback providing a "pretty bad" comparison to modern ARM processors in a recent Anandtech test.
In the more immediate future most Intel based tablets arriving are expected to use the Bay Trail Atom chip which uses the Silvermont cores, this is it's most power frugal design. However we may see some early and interesting efforts with a Haswell processor, it depends on what the OEMs make of it.