Let's just say the overclocking support is LIMITED.
It may be some processors won't overclock at all, but you can overclock the memory on the motherboard.
In general, A320 based motherboards have a weaker VRM (the dc-dc converter which powers the CPU), without heatsinks over the components that heat in order to save money.
For example, with an average 65w TDP processor, the VRM may hit temperatures in the 60-70 degrees Celsius but with 95w TDP, the VRM may hit 90-100 degrees Celsius ... which is very close to the maximums allowed. At 90-100 degrees, the circuit board can degrade over time.
So with a 65w TDP, you may be able to overclock it a tiny bit and still keep the heat generated by the VRM within some reasonable limits but the VRM would probably not output a "quality" voltage to the CPU, and that poor quality voltage would not allow the CPU to reach the maximum performance it can do.
With A320 based boards you also get cheaper (older) sound chips, like only 5.1 ALC 882 or ALC887 instead of 7.1 ALC1020 or whatever, and you don't get a lot of USB connectors (because those also cost pennies and pennies add up)