
Originally Posted by
EximoJul 18, 2016, 3:37 PM
Haswell and Skylake processors are very very low power CPUs at idle. If they are the main power draw in the system (A system with only a core series chip and maybe a single SSD or harddrive the system will draw very little power while booting)
While decent power supplies can provide appropriate voltage at 'no-load' conditions, many cannot, and a system could potentially fail POST due to too high or low voltage being supplied the PC. Or may damage components. PSUs are built to be efficient between 50-80% load.
Further to this, many older power supplies also need to have a balanced output. With those supplies you must draw relational amounts of 12V, 5V and 3.3V. If one is underloaded this can also lead to poor voltage output. These power supplies are generally the tier 4 and 5 supplies you see with wildly inflated outputs. It is because they are including the maximum output of all rails simultaneously, which is almost never possible.