At clock speed 291, LL hashes about 12.8mh/s, 444 watts, still 6% HW errors.
Also, < 1% rejects on clevermining.
I don't have a power meter, could you try at 10.4mh to see what the power use is compared to gridseed blades? And are you using original firmware, or the upgraded one availabe? I haven't upgraded myself yet because jjj0923 said there was some kind of problem with it.
I took one of the Zeus 1.3Mh/s machines down to stock speed of 280mhz (the default OC is 328 I believe) and it was still pulling 50 watts from the wall on a platinum PSU. Consider that 8 gridseed blades pull 737 watts from the wall on the same PSU yet will do 45.6Mh/z at 838mhz and you see the problem. What would it take on one of these things, around 1600ish from the wall to get similar performance? It isn't a clock issue, or a firmware issue, or a configuration issue the chips in these things simply pull way too much power. There is no way around that.