You wrote, "you've seen lot of questions on this subject and few answers". What your experiencing is not an issue with Gigabyte.
G.Skill FAQs:
Q:
I want to install more memory, in addition to my existing memory kit. What are my options?
A:
We do not recommend mixing memory kits, regardless of brand or model.
By mixing memory kits together, there may be compatibility issues such as unable to boot or unable to operate at rated specifications.
Each of our memory kit are thoroughly tested to ensure compatibility within each memory kit. And because we have not tested our memory kit with your existing memory kit, we cannot guarantee compatibility when multiple kits are used.
I have seen some people, i.e. dmdilks, scoff at that and say memory manufacturers are just trying to sell you more RAM. Maybe he can offer you better help. The fact is memory manufacturers do not guarantee mixing multiple kits will work at all or how they will work. Corsair recommends trying to set the memory clock to a slower speed in an attempt to get them working.
You asked, "What are the right settings"? When using multiple kits the memory manufacturers specifications no longer apply. As Corsair recommended, a slower memory clock may get them to work together. DRAM Timings would be guesswork. Some people recommend higher voltages when doing so may just make things run hotter.
Using multiple kits is like doing your own compatibility testing, which can be expensive if things are not compatible. Using a single kit is guaranteed for life to be compatible.
