It should work but make sure the pins are aligned. I googled your motherboard and found this link https://www.asus.com/Motherboards/F2A55M/specifications/.
Adding memory is the easiet and quickest way to upgrade your machine. If this is your first time opening it up and trying something like this - I would suggest taking your time and make note of how the old memory is oriented in the slots. Also you might want to do a benchmark before and after adding/replacing the memory. I wold suggest AJA system test or PC mark8. Also speccy is great to check out all of your hardware, temperatures, etc. CCleaner is great to get rid of files and check your registry. All are free downloads. Good luck and hope the response helps....but I noticed this question is over 2 months old so you may have moved on...