This sounds a lot like what's going on with my Rampage V Extreme U3.1 motherboard which is also paired with a Haswell-E (i7 5960x in my case). My error is more extreme. If I update to the latest BIOS, my 32GB Corsair LPX 3000MHz kit is not even recognized. I have to stay on BIOS 2001 just to pass POST. If I overclock the RAM beyond 2800MHz, I also get the q code "bF". Also, I found that my gaming experience was unstable with RAM overclocks at 2800MHz. So I'm sticking with BIOS version 2001 and running at stock RAM speeds of 2133MHz with my 15-15-15-35 timings.