The S12 means Silent 12cm, and yes, this power supply runs pretty quiet.
Manufacturer's Features & Specifications:
Dual +12V Outputs
120mm Cyclone Cooling Fan > 61 CFM
Patented Easy Swap Connector
All-in-one Connector Design
Dual 6-pin PCI-Express / SLI Graphics connectors
Super High Efficiency: Up to 80%
Active Power Factor Correction: 99% PF
Smart & Silent Fan Control: S2FC
Ultra Ventilation: Honeycomb Structure
Universal Free Input: 100-240V full range
Forward Converter: Advanced design
Cable Management Kit: Dr. Cable
S12-500 / 600 models support 150W PCI-E Video with 6-pin connector
+3.3V: 30A / +5.0V: 30A
+3.3V & +5.5V Combined: 180W
+12V1: 17A / +12V2: 16A
Seasonic has "Twisted & Tidy Wires", which are used for easier installation and reduced EMI. I think that the regular old wires will be bette though.
The main power cable is approximately 17" in length, the other cable range from about 13" up to 18" to the first connector (nearest the PSU). However, in my opinion, the gold would be better.
1 x 20+4pin main ATX power cable
1 x 4pin +12Vconnector
1 x 8pin +12V EPS connector
2 x 6pin PCI-Express connectors (single cable)
6 x 4pin connectors (2 cables)
4 x Serial ATA connectors (2 cables)
2 x floppy connectors (2 cables)
1 x 3pin fan monitoring connector
Included with the PSU is a power cable, manual, 4pin to three 3pin fan adapter (1 x 12V & 2 x 5v), screws, case badge, some plastic sleeving, and zip ties.
Exterior of the S12 500W:
The Seasonic S12 500W has a simple flat black coating & chrome fan grill. The 110/220V selector switch is missing. The back of the PSU features the Seasonic "Honey Comb" design, supposedly for better ventilation.
Full DC output : 12V1 - 17A & 12V2 - 16A
The best part in this psu is the noise level. Its really quiet psu, no matter how much power you are using. The heatsinks are larger than average, which the more surface area, the better the heat dissipation.