The new Signature Series from Antec is a premium power supply line, which means that products from this series (so far 650 W and 850 W models were launched) have tighter specs. For example, voltage regulation is set at 3% instead of 5% (7% instead of 10% for the -12 V output). Between the lines the manufacturer says this line has a very high efficiency, although on the specs table they list efficiency as "80% minimum". Signature 650, also known as SG-650, features a half modular cabling system and only one 80-mm fan, which the manufacturer says is quieter than other 80-mm solutions. Let's see what is really inside this power supply and why it is so much more expensive than other units.

http://www.hardwaresecrets.com/article/658