Hi and welcome to the Gigabyte forum.
These are usually memory errors.
What memory modules have you got installed ?
What slots have yuou installed them in ?
You say you tested the memory but did you do it properly like this?
I would suggest that you download and run Memtest86+ to check your RAM first.
Memtest86+
http://www.memtest.org/Insert one stick of memory in slot 1 and run Memtest on it for at least 10 loops 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.