You can use 6 card mod for windows 7.
https://lbr.id.lv/6xgpu_mod/No need for windows 10.
I would check power consumption with watt meter.
I recommend bigger PSU.
Damn wish I had seen this earlier.
Anyway my rig is still not properly detecting 2 of the 6 cards in Windows 10 now.
Its the two 480s that cause the rig to not boot up and crash. I had to "Reset PC" and disconnect the two 480s to get the rig going again.
Right now Im hashing at 20 mh/s on 4 cards only.
I did do an upgrade from Window 7 and not sure if I should re-install the Crimson drivers now that Im on windows 10.
You can go back to Windows 7 if you want. Just do a clean install and your Windows 7 product key will still work. Once you activate Windows 10, it registers your machine ID so you no longer need to enter a product key to activate it when you reinstall Windows 10 on the same machine. Just skip the part where it asks for the key during setup.
If you want to mine Ethash coins like Ethereum on Windows 10 v1709 (Fall Creators Update), you need to use the latest Crimson Relive 17.1x.x drivers and toggle to the 'compute' mode from 'gaming' for each card in AMD settings. If you are having problems installing the driver with all the cards connected to the motherboard, remove all the GPU drivers in safe mode using DDU and make sure to enable the option in DDU to disable the Windows automatic driver install. Then shutdown and connect only one card to the primary x16 PCI-E slot. Once you install the driver for the one card, shutdown and connect two more cards to the motherboard. Start the rig and wait until Windows detects the cards and installs the drivers automatically. It may take a while for the cards to show up in Device Manager. Wait and confirm in the Windows Task Manger there is no running instance of the Driver Installation Module running. Once the Driver Installation Module is no longer showing in Task Manager, shutdown and repeat the process, connecting two cards at a time until all the cards are shown in Device Manager.
With RX 470/480 or RX 570 cards, you will then need to use the pixel patcher to bypass the driver signature check with a modded Bios to remove the Code 43 error in Device Manager before the cards will work. Just run the patcher, reboot and verify all the cards are shown in Device Manager with no errors.
https://www.monitortests.com/forum/Thread-AMD-ATI-Pixel-Clock-Patcher