This seems to be a stock firmware, so ME region should be OK and ME doesn’t affect graphics output on older systems. I assume this is more like a ‘MUX’ problem as described here:
If you have look into setuputility with an IFR Extractor you find:
…
0x7390F End Form {0B 02}
0x73911 Form: InsydeH2O Setup Utility, Form ID: 0x25 {01 06 25 00 11 00}
0x73917 Subtitle: Video Configuration {02 04 43 00}
0x7391B Subtitle: {02 04 14 00}
0x7391F Setting: Display Mode, Variable: 0x20A[1] {05 09 0A 02 01 1F 03 20 03}
0x73928 Option: iGPU, Value: 0x0 {09 09 21 03 00 00 00 00 00}
0x73931 Option: dGPU, Value: 0x1 {09 09 22 03 01 00 00 00 00}
0x7393A Option: Hybrid, Value: 0x2 {09 09 24 03 02 00 01 00 00}
0x73943 End of Options {10 02}
0x73945 Grayout If: {19 03 00}
0x73948 Variable 0x85[1] equals 0x2 {12 07 85 00 01 02 00}
0x7394F Variable 0x86[1] equals 0x1 {12 07 86 00 01 01 00}
0x73956 And {15 02}
…
BUT: This depends how this mainboard is configured, there were setups where video output was routed through the GPU even if it came from iGPU.