I'm not sure how a different motherboard could affect things, why would my 1660s be ok to use but my 3060ti not ok on the same motherboard for example? Would the chipset affect this?
I did think about buying an cpu+board from ebay thats different to my current setup but the cost is a lot, I could buy another GPU instead perhaps.
The only thing that may be similar is I own two laptops, each has a skylake intel CPU with a HD530 (but one also has a nvidia 1060) but only the nvidia laptop is ok to use, even with graphics switching enabled. The other with just the 530 is not ok on multiple internal and external screens. One is a clevo, the other is a dell machine so different internals / boards.