well i am building a basic PC for my friend .
The Config is
Core i3 3220 [ ECC Memory Supported CPU ]
Memory : G.Skill F3-12800CL9D-4GBXL. but its Non-ECC
Does it make any difference ?
It won't be a problem unless you start mixing ECC-RAM with non-ECC RAM.
However, if a board supports ECC-RAM you really ought to take advantage of that as it will provide greater data integrity.
If you do decide to use non-ECC RAM on a system that supports ECC RAM, you may have to specify non-ECC memory in the BIOS settings, depending on the specific memory controller and how it initializes memory.