You should change your risers first of all. I had bad luck with shitty risers months ago. Sometimes the card appear sometimes not. I thought the problems were elsewere but after changing two (!) packs of risers finally the problems dissapeared for good. The next thing is to use windows 8.1 64 bit, especialli if you have h81 mobo. They are really well optimised for this OS. Moreover, windows 10 will have bigger load on the cpu which can slow your cards when mining. In my case win 10 is above 90% whereas win 8.1 around 20%.

You should see 6 cards after the drivers install and 1 probably with an exclamation mark in the device manager. You need to run the 6 card mod to be able to mine with all 6.