Virtual-Hideout has posted a review on the Ultra Products X2 550w Modular Power Supply

Ultra went the extra step in the cabling department in using
all the exact sized (not same sized) connections for ALL the modular cabling
system. Meaning, the dual 6-pin PCI-e modular cables each have their very own 6-pin connection on the body. Same goes for the 4-pin 12v ATX connection, the 4-pin molex connections, and so on.

Ultra Products X2 550w Modular Power Supply Review