I have one rig with such cards and I patched them back in December 2017, so I probably forgot the exact steps, but I will try to remember. They mine at 32.2 MH/s with PhoenixMiner. By the way, one of them burned out like 2 months ago, I don't know why.
To patch the BIOS, I used PolarisBiosEditor, version 1.6.6. I don't remember from where I got it, but it has a button ONE CLICK TIMING PATCH. My settings look like this:
http://prntscr.com/mb51k7 I remember playing a lot with the voltage settings to lower the power consumption and I obviously modified them, but those GPUs still eat a lot of electricity - almost 1 KW (6 GPUs). Now that I have only 5 of them, they consume 800 W from the wall.
I used DDU (Device Driver Uninstaller) every time I wanted to install new drivers. Otherwise it becomes very messy, especially with nVidia cards. For the drivers, search Google for "amd blockchain driver". I see I have a file named Win10-64Bit-Crimson-ReLive-Beta-Blockchain-Workloads-Aug23.exe.
After installing the drivers, I used some tool to patch them. The file I have is named atikmdag-patcher-1.4.6.zip. Without this, the hashrate is lower.
