Not hashing @ full speed

today I received 2 blades,
But whatever I try, they re not hashing @ full speed and average around 6000 Mhash

Total MHS:   06285
Received:   0000003257
Accepted:   0000002344
Per Minute:   087.35
Efficiency:   071.96%
Up Time:   0d,00h,26m,50s

Current Server: 10.10.20.66:8332
Clock selected: Low
Chip: OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
IP   10.10.20.107
Mask   255.255.255.0   
Gateway   10.10.20.1
WEB Port   8000
Primary DNS   10.10.20.1
Secondary DNS   211.148.192.141
Ports   8332,8332
Server addresses 10.10.20.10,10.10.20.66   


I Measured voltage on PSU: 11.5 - 11.7V,
tested with one blade: same result
PSU = OCZ 700W
the voltage measured on the 2r2 resistor  = +/- 1.06 - 1.065V
I have 2 stratum proxys on 2 PC's and the blades change server every x seconds it seems. If I refresh I see that they are using the other proxy a lot of the time. this is not normal I assume? Is it possible a problem with internal networking?

when the blades swith over to the other proxy I see this: 013-09-05 01:32:50,571 INFO proxy client_service.handle_event # New job 27024 fr prevhash bc0f8289, clean_jobs=False