Every motherboard OEM has a webpage for each board, on that page is a list of tested ram modules (often under support section/tab)
These are modules that the mobo manufacturer has tested and approved on their board.
Does not mean that others wont work, but it means if you get ram in that list it is garanteed to work.
Not getting ram in that list is can be risky as you may very well get stuck in limbo between the ram and mobo vendors poitning fingers at each other instead of issuing you an RMA if you ever need it.