Gents, I'm having a problem adding a second PSU to run card #5(and eventually 5-8). I have 4 64s powered by a corsair 1200i, getting 8k hashes total. I'm using an add2PSU to connect two corsair 1200s. Whenever I add my 5th card using my secondary PSU, it goes unrecognized in windows. The 'Radeon' lights up, but there is no red light near the power cables.

To troubleshoot, I changed all connections to my second PSU so it acts as primary and it powers 4 cards fine. I've also added 5 cards to each PSU and they all hash fine - however it's far too close to the max watts. One time I switched two cards to the secondary psu - one card had all red lights on, the other just a green light but neither were recognized. The fans don't spin.

The problem lies with trying to get any cards in attached to the secondary psu to be recognized in windows. I'm using s Biostar Tb-250 pro. Anyone have any suggestions?