I am having a similar problem. My R7 shipped about a year ago with 32GB (2x16GB HyperX Fury 2933DRAMs) and was shipped with the ram running in XMP 2 mode at 2933MHz. I upgraded from 32GB to 64GB by adding two additional HyperX 16GB Fury modules (HX434C19FRK2/32) to the two empty slots. The addition of those two modules forced XMP mode in the advanced settings of the BIOS to "DISABLED" and it also eliminated the "MEMORY" adjustments button in the OC Controls where I would create a custom User Profile. It also rolled back the 2933MHz clock frequency that my memory was running at to 2400MHz. As an experiment I removed the original modules and replaced then with the two new modules to see if I could get back to the original configuration of 32GB running XMP2 at 2933MHz with the new modules. This was successful (at least at first) so it was clear that these modules could run at that speed. Interestingly though, after a few cycles of moving things around I found that the computer would no longer boot with the new modules in the slots where the modules were originally shipped and I started getting the 4 blink error code. It's like the computer finally caught on that these were not the modules shipped from Dell. Very strange. My final configuration, though very disappointed, is that I now have 64GB ram but am only running at 2400MHz. My BIOS version is 1.0.18.