If you remove the old system memory, again, most likely. You would then have 16GB of memory. If you already have 4/8/16GB and you want to add more, mixing memory doesn't always work. And if it does, generally it will default to the lowest speed that both sets support. With LGA1150 that is probably going to be 1333, but 1066 is also possible.
OEM BIOS don't always offer the necessary features to re-configure the memory to run at faster speeds, and even then when mixing memory you often have to do it by hand, which might not be possible with the Acer board.
More memory only makes a computer faster if you can utilize the extra memory. If you aren't running out of memory now, adding more won't do much.