Why can't a power supply supply low current?
From the article:


  As it appears, Haswell's C6/C7 states require a minimum load of 0.05A on the 12V2 rail, and many desktop power supply units (PSUs) just cannot provide that low current, reports The Tech Report web-site. Meanwhile, numerous older PSUs, which comply with ATX12V v2.3 design guidelines only called for a minimum load of 0.5A on the CPU power rail, hence a less sophisticated internal feedback loop/protection could be used, reports VR-Zone web-site. As a result, unless C6/C7 power states are disabled in the BIOS, PCs with older/cheap PSUs may become unstable when processors enter these states.


A minimum load specification signifies the smallest load that can be drawn from the power supply while meeting all of the other requirements in the specification (regulation, transient response, etc.)

The power supply may or may not be able to deliver less current than what is specified as its minimum. It may deliver but drift out of voltage regulation; it may become unstable and oscillate; it may hiccup on and off; it may even go into overvoltage protection and latch off. Because the load is outside the specification, "anything goes".

The article's statement "just cannot provide that low current" is (to me) a gross simplification of the matter, and is a bit misleading. Current power supplies were never designed to meet this specific condition, so behaviour at this condition is undefined.