Nope - bigger issue. According to Biostar re: B350 BTC MOBO - official AMD driver for RX580 has a limit for 5 GPU, so if you are going with Ryzen's you may need to rethink your GPU.
if you use the method of downloading an earlier driver and over lap the newer driver, it has worked for me recognizing 6gpu's, i have used different drivers then mentioned here 17.5 but should work the same.
I was able to get 6 x RX-500 series running on windows 10 x64. After two days the stupidest thing I tried worked
.
1. use DDU to clean the PC from any previous drivers.
2. Disable 4G decoding so you can log into windows (only for Z170,H170, etc.)
3. Extract older driver for RX 400 series in Drive C: (I use 16.9.2 )
4. Extract driver for RX 500 series in Drive C: (I use 17.4.3)
5. Copy and replace all content from "C:\AMD\Non-WHQL-Win10-64Bit-Radeon-Software-Crimson-16.9.2-Sep21\Packages\Drivers\Display\WT6A_INF\B307117" to "C:\AMD\WHQL-Win7-64Bit-Radeon-Software-Crimson-ReLive-17.4.3-Apr17\Packages\Drivers\Display\W76A_INF\B313057" (Basically you copy the old driver over the new)
6. Install the VGA cards manually from Device manager in Windows pointing path to the new driver 17.4.3 in this case.
7. Reboot and enable 4G Decoding in Bios
8. Enjoy if it works for you.