What makes this power supply "Express."
As far as I know, all of the PC Power and Cooling Turbo-Cool
510W power supplies are the same except for the cables and the access holes
for the voltage adjustment potentiometers.
The "Deluxe" takes the cables of the regular 510 ATX
and puts a weave over the wires. The "Express", as reviewed, features
a 24-pin ATX/EPS connector and one PCI Express connector. It also
features 6 SATA connectors as opposed to 2. The "SLI" model has two
PCI Express power connectors.
Furthermore, the Deluxe, Express and SLI all have little
holes drilled into the power supply housing where a small screwdriver can
inserted and voltage can be adjusted.