I've had my 8 s9's for about 6 months now so far I've had to change 1 control board and from what it looks a second one will be going out soon as well as 1 hashing board that I have to send for repair now and not to mention that 2 or 3 ( don't remember) s9's have completely failed on me , that was within the guarantee time so I got them repaired for free but at the same time I had to pay around $70 to send each unit back by EMS and wait for about a month and a half to get it back.  It took them around 2-3 weeks just to confirm that they've received them. Now that they have a repair center in the U.S I'm sure that things might be faster but I don't know.


In my case from what it looks the control boards keep going out when the electricity keeps getting shut off very often or because of spikes, I think it can even brake just from some static electricity so I wouldn't recommend you touching it too much.  It is important to have a good power supply so don't be stingy and get a good one right away or it will cost you more later and having an extra power supply is a good idea as well as having an extra control board so that if one of these 2 brake you won't loose BTC, waiting or even looking for them.  Waiting for some parts or for your unit to get repaired is the worst thing!  I hope I didn't discourage you too much but it is the reality.  I keep my miners as cool as I can but where I'm located even with a special cooling system I can only have the room temp at around 27c and max I try not to get it go beyond 31-32c and I can tell you that at 27c they seem to work a lot more stable and even put out more hash.  

Hope that helped! Happy mining!