wild card is right about ram , I only have 1 gtx 1080 and I have 16 gb ram , he is also right about sli , if the rest of your gear is not up to the job 2 cards can perform worse than 1.
you not mentioned the games you have , are they by any chance frame locked by the makers.
Do you have GTA V , on my zotac version of the 1080 card I can get 110 to 145 fps using the built in stress test program.
Your point 9 ... pro over clock 10% are you saying the 2 1080's are overclocked by 10%.
I found a program on my g cards disc that I thought was a game , it turned out to be an overclocking program.
As I know nothing about oc I emailed the company and the "individual" who replied said and I quote " I don't know why somebody put that on the disc because when put under severe load the 1080 has the ability to overclock itself". As I as I never tried it I am only repeating what somebody elses opinion was.
footnote I don't use the nvidea experience program its a pain in the ….. , I always manually download the driver update and use custom install to untick the experience part of the program.