Ok, I hooked up my 10 Ohm 25 Watt resistor to the 12V line of my 300W ATX PSU, and with the paperclip, and no load on the 5V line, I got 11.58 v on the 12v line. (tweak time!)
The resistor warmed up rather quickly
I'll still try adding a 1 Ohm power resistor on the 5V line, to see if it changes anything.