Running 6 here all flawlessly for months.
3 bought direct and 3 bought from here all running at around 1.3TH/s

As for them not running at 1.7TH/s when i first got them and just because I wound everything up to 11 i got 1.6, 1.68 and 1.77.

They are far happier at 1.3TH/s and so are my power bills.

I'd like more but we'll more chance of pigs flying..