Question Which XFX graphic card will be better?

The specs on the Merc are higher you're paying extra for the white and the magnetic fans.

Also,will it be a problem of I use that card on pcie 3 port? I have msi mortar b660m.
The board in question is this;
https://www.msi.com/Motherboard/MAG-B660M-MORTAR-DDR4/Specification
correct? If so, you have support for PCIe4.0x16, what processor are you paired with that motherboard? Or are you referring to the lower PCIe slot on the motherboard? If so, what's stopping you from using the first PCIe slot?
 
The specs on the Merc are higher you're paying extra for the white and the magnetic fans.

Also,will it be a problem of I use that card on pcie 3 port? I have msi mortar b660m.
The board in question is this;
https://www.msi.com/Motherboard/MAG-B660M-MORTAR-DDR4/Specification
correct? If so, you have support for PCIe4.0x16, what processor are you paired with that motherboard? Or are you referring to the lower PCIe slot on the motherboard? If so, what's stopping you from using the first PCIe slot?
Thanks for the reply, I have the same motherboard that you have linked and I have I7 12700 CPU. Also I am referring to to the last port in the bottom of the motherboard, while I know that I have pcie 4.0 x16 I have noctua NH -d15 cooler and it is blocking that slot and pretty much the slot under it to leaving me only with the bottom slot to use. That is why I asked will it be a problem if I use the new GPU on that slot in the bottom or will I be losing much performance.
You can take a look at what the situation of the setup of you want:
View: https://imgur.com/a/6V49xAn