found this on a site....
ATX 1.0 12V PSUs included:
20-pin connector (2x10)
P4 connector
ATX 1.3 12V PSUs include:
20-pin connector (2x10)
6-pin AUX
SATA connector available
P4 connector
ATX EPS 12V PSUs (server PSU) include:
24-pin connector (2x12)
P4 connector
8-pin (2x4) server connector
ATX 2.0 12V PSUs include:
24-pin connector (2x12)
P4 connector
SATA connector standard
6-pin (2x3) PCI-E connector
ATX 2.0 is the new standard. Most current motherboards don?t require it, but P4 motherboards w/ PCI Express do. ATX 2.0 is backwards compatible to ATX 1.3 motherboards, if you use a 24-pin to 20-pin adapter, often included with ATX 2.0 PSUs. ATX 2.0 PSUs have done away with the 6-pin AUX connector included with ATX 1.3 PSUs.
20 to 24 pin Adapter - needed for ATX12V2.0 compatible (not compliant) power supplies without an adapter - example: previous version of the NX-4090
6 Pin PSU PCI Adapter - needed for your PCI Express Video Card with ATX power supplies which are not ATX12V2.0 compliant