Just finished building my first gaming PC. Thanks to the manual, success!
CPU - Intel Core i7 4770k
Motherboard - Asus Maximus VI Impact
Memory - Corsair Vengeance 16gb 2x8 1600
HDD - 1 TB WD Caviar Black
Case - Bitfenix Prodigy Midnight
GPU - Asus GTX 780
PSU - Seasonic Platinum 1000
Cooler - Corsair H100i
Note: I don't know how to overclock :-)
1. What if I'll buy a new set of memory, 2133mhz or higher? What should I do to make it compatible with my system? Will it make my PC run faster?
2. Do I need to overclock the CPU if the memory is overclocked?
your board may well handle 2333 ram but your cpu doesnt. it handles a max of 1600 so any bandwidth thats available over and above that is ignored. it will make a difference in benchmarks where higher numbers mean better but in the real world there is no benefit from going over the max supported ram your cpu allows.
for your system thats ddr3 1600. so i would recommend you either buy ddr3 1600 or get some 1866 and run that at 1600 with lower latencies. either way will give you the max the cpu can handle.
If you mix memory modules with different clock speeds, the mobo will automatically throttle the faster clock down to the slower clock. So it is pointless to buy 2133 MHz RAM if you intend to use it at the same time as the 1600 MHz RAM.
Generally speaking however, for gaming you don't really need anything higher than 1600 MHz. You might see a slight improvement going to 1866, but definitely after that the return on investment is vanishingly small.
You don't need to overclock your CPU if you memory is overclocked.