The 1600 memory standard is the fastest memory it will support at stock speeds, If you get any thing faster it will run at 1600 stock, IF you overclock you will be able to reach the speed of the faster RAM.
The 1333 RAM will work with the i3-540, and that board. If you are going to overclock get faster RAM so you can reach the CPU limit before the RAM limit. Some 1333 RAM will do 1600 but not all, Some will only go a few MHz faster then specs.
The bad thing about this board is the PCIe x8 slots do not run at x16 with 1 card. Unless you are running a top of the line GPU it will not saturate the PCIe lanes. But for the cost its not bad.
So does that mean 1600 RAM will work with i3-540? Or will only stock/overclocked 1333 will work?