After some hours or days of the miner running you should be at 1.6th. Its normal to have peaks and drops though. One of my cores that was overheating at 120c would still be hashing fully. I would suggest not opening your machine unless it is overheating. If you notice overtime the temps getting hotter and hotter and hotter then most likely its on its way to overheating. Let the miner run as long as possible until it nears or hits 120c and you have no other option but to open it.