Also, a second question.
How many risers is it safe to run off 1 strip of Sata plugs out of the psu? Ive seen youtube build videos where people say no more than 2... others say no more than 4?
I would say this depends on the risers and actual PSU used as well as the card plugged in the riser. What you can do is connect the sata to 6pin and run the rig for a couple of hours to see how hot the cable got over this time and then see for yourself how many can you put in. In my opinion those connectors just physically can't burn if they don't get warm over some time.
On the other side I would also recommend using a server PSU and not using 6pin to sata cables at all , this way you will get rid of another failure point.