I was told that I need more than 4gb to mine with 5+ cards. I currently have 4gb and am able to mine with 4, but couldn't get 5 cards to mine yet in win7. I tried the 6gpu hack and it did remove the error 43 in device manager for the 5th card but I still couldn't mine with it.
I was trying win10 for 5cards but couldn't get it to stop freezing with my rig (I think this is a driver issue as I had similar freezing in win7 until I updated from 15.12 to 16.4.2.
Anyway do you guys know if I need more than 4g for 5card mining?