There is no difference and you wont benefit from having 32GB of ram its complete overkill (Yep even tho i have 32GB  ) unless you are doing some serious heavy load and applications that require a lot of RAM , most games don't even use 8GB.

Strange, It might have just been an issue with the way it was detecting them, Did it ever boot with just 1 titan in slot 1?

Hi Nameis2short,Does it happen when you'r laptop is plugged in?This will also helphttps://msdn.microsoft.com/en-us/library/windows/hardware/ff559329%28v=vs.85%29.aspxYou can use their Driver Verify tool which may help to solve the problem

It looks like expansion slot backings but not to sure, Might want to ask ASUS Support and if they are important go back to the Seller and request your money back

Have you tried rolling back the nVidia driver and see if that works?