Yes, I think red 5v, yellow 12v, orange 3.3 You have to jump a few pins and if it's not connected, supply a load (resistor) to the 5v.... i use them for Plastic printers, etc.
Hopefully the power on sequence will not be a problem.
Here's an example:
http://www.electronics-tutorials.ws/blog/convert-atx-psu-to-bench-supply.html
FYI, if you need cheap high current 12v (like to hook up heated seats in the house?) dell server supplies are cheap on ebay, and put out 50-60 amps.
