Help with iGPU and dGPU

Hi guys, im very close to a golden build for my system, details below. I have one issue left to iron out which is I cant boot with both my iGpu and dGPU enabled. Error i get at the start screen is memory allocation error.

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Does anyone have a guide on how to enable both for a z390 chipset, everything else seems to work, no lockout or crashes except sleep/wake is tempremental and works sometimes but doesn't others so im thinking maybe this change can help. Im using the smbios iMac19,1 which my system is very close to except on that system i believe both gpus are enabled.

Intel 9700k

Gigabyte Auro z390 Ultra

Samsung Evo 7 500GB SSD

16GB 3200 DDR4

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PCI Slots

1 x Alpine Ridge Thunderbolt

1 x Fenvi t919

1 x Intel 700 series SSD

1 x AMD Asus Strix Vega 64

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Water cooler

Samsung 4k TV plugged into HDMI on Vega 64

USB Keyboard and mouse