There are some BIOS settings you should set:
1. Update BIOS to the latest version (or at least 06XX)
2. Disable PCIex power management
3. Set to Gen2 everywhere you find it (4 places)
4. Disable HD audio, serial port
5. Set primary display as PCIE
6. Set M.2 as PCIE
7. Enable Above 4G decoding