I am a bit confused over the terminology and efficiency rating of a power supply. For instance, under 100% load my 1200W 80+ Gold power supply is listed to operate close to 88% efficiency. What does the 88% efficiency rating apply to: the power consumption measured at the wall, or the power consumption measured at the interface points to the computer?
I initially assumed it was the latter but I put together a system that measures a 1040W power draw at the wall (with a Kill-A-Watt meter). At this point, the system starts to become unstable and eventually shuts down. I suspect the need for more power since 88% of 1200W is 1056W -- conspicuously close to my measurement.
Edit: I am using a Corsair AX1200 80+ Gold power supply.