So you had no problem using the secondary/slave power supply to run your video card. I've been considering this with a couple of power supplies that have enough wattage, but not enough amps on the 12V rail to run my 'new' 8800GT OC2. Also wondering if I could use power from both rather than just one. Someone somewhere said something about risks and the power supplies having a common ground.
Also, how did you connect the 14 to 14 and ground to ground? Did you short the power good pins on the slave?