Hi and welcome to the Gigabyte Forum.
The first thing to do would be to prove that all your modules are not faulty. You will need to run the latest version of Memtest86+ for that and please do it EXACTLY as described.
Memtest86+
http://www.memtest.org/Insert
one stick of memory in
slot 1 and run Memtest on it for at least
10 complete loops/cycles and if there are no errors then swap it over with the next one and continue untill you have checked all modules.
If you have any errors the module is faulty.
If you have any faulty modules you will have to return the whole kit as they are matched.
Post back when you have done that with the results.