Intel Haswell's idle states reportedly won't play well with some power supplies
 

One of the staples of Intel's upcoming Haswell processor architecture is its support for lower-power idle states that can rival tablet chips in power consumption, even on the desktop. However, that may come with a big caveat for budget and custom-built PCs: certain power supplies might not cut it. VR-Zone claims that those idle states require as little as 0.05 amps of current, which could be too nuanced for older or cut-rate supplies that deliver power in bigger clumps. That might not be a problem for companies building complete PCs, but Corsair's Robert Pearce tells The Tech Report that it may lead to a lot of motherboard builders playing it safe by disabling those specific modes by default. Many of us, in turn, would either have to buy a fresh supply or toggle the power-saving options ourselves. We've reached out to Intel to verify the truth, but it may be wisest to make a cleaner break from the past with any near-term upgrades.

http://www.engadget.com/2013/05/01/i... ign=Engadget