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Arguably the most important new feature of Intel's upcoming Haswell processors is the extremely low idle power consumption. Well, ARM would like to tell you that it's not really that low, but by the traditional standards of high-performance x86 processors, Haswell's idle power consumption will be very low, and possibly the lowest ever.
This is mainly useful in laptops, as if you can reduce the idle power consumption by a watt or two, you can extend battery life considerably. In desktops, it's not such a big deal, as if your processor uses a few watts at idle, so what?
But then it recently came out that in desktops, it could actually be problematic. If the CPU power connector pulls a small fraction of a watt, will power supplies be able to keep the voltage suitably stable? If not, then the computer crashes. This is a bad thing. If this sounds like a trivial concern, it might not be, as apparently some power supplies can't.
So naturally Enermax quickly jumped on this and announced that their high end power supplies are all completely compatible with Haswell. They didn't mention their mid-range to low end power supplies in this announcement. Seasonic more recently did the same. Now Corsair has as well, and unlike Enermax and Seasonic, Corsair actually mentioned that they have more budget-friendly power supplies. Of course, Corsair didn't say that their budget power supplies support Haswell, but only that they likely do but they're not sure yet.
This might all be much ado about nothing. If some $15 Diablotek or Apevia piece of junk crashes when Haswell goes idle, so what? It's not like it would be safe to use at any other wattage.
And even if there are a lot of decent power supplies that genuinely don't support Haswell's low idle power consumption, it will be easy enough to fix in the BIOS by disabling the C-states that Haswell would normally try to use at idle. Artificially increase the idle power consumption so that Haswell uses a few watts at idle and the problem is solved. If this turns into a major issue, I wouldn't be surprised to see motherboard vendors ship BIOSes that disable certain C-states by default.