Intel has confirmed that 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.

Less than a year ago Intel announced its intention to deliver Intel Core processors operating at less than 10 watts and two months it delivered 4th generation Core processors operating at 6 watts scenario design power (SDP).
BR> Remember that the 4.5W and 6.5W thermal ratings refer to scenario design power, or SDP. Processors are usually tagged with TDP ratings that describe their power usage during short bursts of activity. SDP describes power draw for sustained workloads.