In no particular order:
- USB storage boot device compatibility
EPYCD8 seems extremely picky about USB storage devices it will successfully boot from. I tried a USB3 Zalman DVD emulator, and a few different USB sticks. Most start to boot but error out before they can finish loading the kernel. Eventually I found an older USB2 memory stick that seemed to work OK. The problem seems to be with the BIOS, as after the kernel and the USB controller driver load, everything works fine, including high speed USB3 devices, without any errors.
- Display output with multiple GPUs is wrong
When an additional GPU is added, if Asrock boot logo is disabled, no display output showing the boot options (e.g. Del/F2) appears, and BIOS setup doesn't display. At this point the only way back to a BIOS configuration is a full CMOS reset via a switch on the motherboard (not all boards have the switch soldered on, shorting with a paperclip is required if the switch is absent.
Additionally, when an external GPU is present and the boot logo enabled, this always shows on the external GPU, even when the primary display in BIOS is set to on-board.
- No legacy option ROMs display when an external GPU is present and their configuration is inaccessible (e.g. SAS controllers).
- With 7xx2 CPUs, all manual CPU configuration options are ignored, including TDP limits, boost clocks, custom P state clocks and voltages.
It would be really useful if at least some of these bugs could be fixed in a future BIOS update.
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