I already knew (or so I thought) that gains or losses from different memory speeds and timings made only a small difference in real-world performance, but the allure of something faster is a hard bug to shake. I grabbed some G.SKILL Ripjaws 2133 CL11 memory to replace my Kingston PnP 2133 CL12 fully expecting to see a very modest improvement in performance for my already insanely powerful M18xR2. Unfortunately, the opposite was true. There was a substantial decrease in performance... enough to be seen and felt.
I have used G.SKILL memory many times in the past and it has always been great. The Ripjaws was 100% compatible and rock-solid stable. It booted with no BIOS adjustments (all "auto" settings) and ran at advertised speed without any drama. The decline in performance was a disappointment, but NewEgg issued an RMA promptly. I am sharing the results so nobody else makes the same mistake. The images in the album below speak louder than words.
Tests were run repeatedly to confirm there was no anomaly. All BIOS settings were identical between the different brands. I alternated HyperX > Ripjaws > HyperX > Ripjaws and the differences were consistent in all tests.