First just try one card at a time on your PSU.
Each blade takes 100W off the 12v line of your 550W PSU.
A 550W PSU can have around 15A to 20A on the 12v rail which is around 180W - 240W
Try each card in turn, one at a time. Some cards may be faulty.
I now have 3 cards hashing at around 7GH/s each, running off a 750W PSU
the other 2 cards, power goes into them, lan flashes but can't get the config screen to load for them. I've done factory reset to ensure the IP address is correct, and tried each card one at time... but the config screen just won't load. So... approx 21GH/s hashing OK.
