It's not desktop RAM if it's full buffered ECC because ONLY servers and maybe some workstations use full buffered RAM. If it were just ECC there wouldn't be a problem.
Fully buffered RAM has a different pin and notch configuration so if you tried to use it you would break the RAM and/or the motherboard and even if you didn't it wouldn't work. Go to Wikipedia and search FB-DIMM and that will show you info on fully buffered RAM if you're interested.
How much were you planning on paying?