I am mining for a hobby so please do critique me for mining with a GPU (I know GPU mining is dead but I want to try it anyway), but I have 2 GPU Radeon R9 290 and 2 GPU Radeon R9 290x both made by Gigabyte, Can I put both of these into one mother board and mine or do I have to connect them to two different mother boards because they are different cards? Simply put can a person build a mining rig with two different GPUs?

Also on the motherboard is there any difference in speed between a 3.0 and a 2.0 connection for a pci connection?

Thanks in advance