Greetings! I've chosen to own one of these babies myself due to it's vast amount of gorgeous features.
Yesterday I got a 2nd G.Skill DIMM 4 GB DDR3-1600 (F3-12800CL9S-4GBRL Ripjaws) and installed it into the first red channel (Channel-B1).
I used 3 of exactly the same modules in a Triple-Channel configuration on a Sabertooth x58 board, worked brilliantly.
Now on the Gene-Z board the only thing I get is error code 45 all the time; except if I use both modules in a single channel configuration (B1 + B2).
I remember when I installed the first module; as it worked only in the second red channel slot (Channel-B2) which seems very strange to me.
I've read several threads about the Gene-Z but unfortunately I have not found any solution to fix this issue. BIOS 0403 is also flashed, as I've tried with earlier versions as well.
Note: G.Skill F3-12800CL9S-4GBRL Ripjaws are imprinted with "designed for socket 1156, compatible with socket 1155 sandy bridge"
I've also tried using slightly higher voltages for DRAM and Memory controller as well as lower frequency configurations and higher RAM timings - still the same.
I have also tried a Dual-Channel Kit from G.Skill: F3-10666CL7D-4GBRH, Dual-Channel Slots simply do NOT work - error code 45 all the time!
If there is any possible solution or trial&error procedure you've come across regarding similar issues, please advise.