Hi there,
the reason that there is no straight answer is because running RAM above 1333MHz is not straight forward. This applies to both AMD and Intel platforms. It is also very much dependant on which CPU you are using and if you are planning on using more than two sticks of RAM.
Whatever RAM modules you use, you will need to alter the settings in BIOS to achieve their rated speed above 1333MHz.
It is easier to get the rated speed of RAM if you are only using two RAM modules and if you really want to run at 2400MHz, you will probably need to overclock the system a bit, not necessarily the RAM, even if you buy RAM that is rated at that speed, to achieve the desired result.
In reality, you won't notice any real difference between 1866MHz, 2133MHz & 2400Mhz RAM. The difference might only be noticeable in benchmarks rather than day-to-day usage of the PC
If you want to populate all four slots on the motherboard with RAM, then you may find that you also need to overclock the voltage on the RAM and possibly the CPU a little, to reach the rated speed.
