I let it working last night on 3 boards, and monitored the BTCGuild website until approx.. 10:30am when I had to travel, when arriving now found that is completely off and BTCGuild shows that it stopped around 12:00pm, it works on 3 boards for almost 14 hours and suddenly stopped, see below:

I received a new CX750M and will try using both, one for each pair of boards, if it works for the next 24 hours without issues means this units does not consume what is advertised but a lot more. If it keeps doing the same will like to know if there is any return policy.