Prior to installing A12 BIOS, did you go into the A11 BIOS, open each screen and write down the current settings, then compare those to the settings in A12?

Examples =
Advanced- Performance Tuning. Set to Normal or OC1 or OC2?
Advanced- Processor Configuration. All set to Enabled except for "Limit CPUID Value"

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Run the PC pre-Windows diagnostics
Run the Monitor Reset & BID (Built-in Diagnostics)
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