That isn't true... at least not from what I've read elsewhere on these forums. Taken from vingochr
"11 Inch MacBook Air
The current 11" MBAs have 1.4 and 1.6GHz Intel Core 2 Duo CPUs with GeForce 320M iGP, with a TDP for CPU/iGP combo is 10+12=22W.
Therefore, most logical processors are the ultra low power Sandy Bridge mobile processors, i5-2537M, i7-2617M and i7-2657M. At current price points, it makes sense to go with the i7 chips, the i7-2617M and i7-2657M at 1.5 and 1.6GHz each. These are dual core and two-threads-per-core (2C/4T) and have a TDP of 17W,
5W less than currently required. "
https://forums.macrumors.com/threads/1103979/