Hmm, that's rather sarcastic reply.
Actually, when purchasing a PSU, one should take into consideration the entire system specification, the intended purposed of the system, and the quality of the unit itself. Just because there are multiple of X wattage units with Y amps on the +12v rail doesn't mean they are all the same. Is it measured at peak load or continuous load? Is it rated for 50C or rated for only 25C? Is it one of the lower-end unit that touch the ATX specification limits without exceeding it or is it's a high quality unit that can output much more than what it is rated for while still being within specs?
These factors aren't told to you by the manufacturer, so you can say it the manufacturer already have taken into account all of this for the worse case scenario. What the manufacturer doesn't tell you as well is whether the recommendation is base on the i3 or an i7 3970X.
That's interesting, because you didn't specifically argue about whether a 500w with 40A unit being capable of powering an ITX build with a 4670K and a 770 or not, but rather you were arguing that it will be unable to solely based of the recommendation of a SINGLE component provided by NVIDIA. You even stated that it would cause stability issue with high-end PSU as well... A group regulated design power supply with 42A on the +12v or a DC-DC regulated unit with 40A. The one would run into stability issues first would be the group-regulated design - that 2A or 24w won't change that.
Edited by qwan456 - 11/16/13 at 8:35am