You need to buy 2 x 16 GB of RAM as the motherboard has only 2 slots. All brands should work, but make sure you buy DDR4-RAM with DIMM 288. Also do not buy higher then DDR4-2666 otherwise you'll have to go into the bios and adjust things. Be warned though that this is easily going to cost you 400.-. You also don't need 32 GB, unless you're doing heavy video editing. At the current prices it's a good idea to wait until next year, when the price have (hopefully) returned to normal.