Which one of these RAM?


From G.SKILL's website both the F3-12800CL9D-8GBXL and F3-12800CL9D-8GBRL have exactly the same primary memory timings of 9-9-9-24-2N so there is no difference.

It's just that Newegg.com did not show/specify the DIMMs 2N Command Rate for the F3-12800CL9D-8GBXL.

Command Rate: Also known as CPC (Command Per Clock). This is the amount of time stated in number of clock cycles allowed from when the chip select is executed and the memory access commands can be issued. The lower this specification (1T or 1N) the faster the performance (i.e. approximately 1% to 3%), but 2T (or 2N) is used to maintain system stability. On Intel based machines, 1T (or 1N) is always used when the number of banks per channel are limited to 4.