Question cpu and gpu compatibility

[kissmyassis]

is amd a6 7400k compatible with rx560 4gb?

 

[tennis2]

Yes.
Is this an OEM (Dell/HP/etc) or a custom built machine?

 

[CountMike]

is amd a6 7400k compatible with rx560 4gb?

It's only MB, PSU and case you have to worry about, MB needs to have a PCIe x16 slot, PSU enough power and case enough space. CPU is irrelevant.