Trouble with hd 7750 gpu

I have an Optiplex 7040 running Big Sur with oc 0.7.4

i7 quad, skylake 64 gb ddr3 ram apple broadcom wifi/bt dGPU: gt 730

I am trying to switch to a MSI R7750 (amd hd 7750) dGPU and followed dortania guide and advice on boot args to make this work. It is a supported card.

When I put the card in and boot from OC, the gpu is initialized, can be seen and managed in display preferences, and even shows its being used in iStats.

Unfortunately I only get a black screen on monitor. The backlight is on and monitor detects a signal.

Any ideas?

submitted by /u/zenpathfinder
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