To mine ETH you need a minimum 2 Gb RAM per card, otherwise the DAG won't load into the cards's memory
Might be specific for this miner, I was mining Ethereum using QTMiner on a machine that had 1 GIG of ram in the machine (and a 2 Gig GTX960).
It had to do some special manipulation stuff on the DAG per some of the messages I saw out of it, which meant the first DAG took bloody near forever to get set up, but it then mined successfully for a while (I ended up moving the card to a different machine in a "consolodation" move after a couple days).
I would RECOMMEND at least 2 GIG main system memory to avoid this issue, though.