Asrock IMB-180 above 4G decoding

[Karalux999]

Hello, i have AsRock IMB-180 motherboard with QM87 chipset and AMI Aptio 4 bios and i was wondering if it is possible to implement the above 4G decoding function in my bios since it seems like AsRock wanted to do it in bios update 1.70 (AMIBCP shows 2 bios strings - one for Above 4G Decoding setting and other is the description but there is nothing about 4G decoding in the setup section or anywhere else in the bios image). I want to enable full support for the resizable bar to squeeze some more performance from my old RX 590, i already added rebar dxe driver patch to the bios but it lets me use only up to 1gb for rebar out of 8gb without above 4G decoding.