Is the ram im looking to buy compatible with current ram ?

it's generally a MUCH better idea to have ram from same manufacturer with same specs. They MAY work or they MAY just crash your ssytem and make it very unstable. It's your call....

but, at that price you could buy a kit of 2x8gb ram sticks from newegg for a few bucks more and have no worries.
 
Will it run without issue if you put it in the board by itself? Yes.

Will it run without issue if you put two of it in the board and remove the other unknown stick? Yes.

Will it run without issue if you put it in with the other unknown stick? Probably but I can't guarantee it.

If you have an Asus board, you have this wonderful button called MemOK! that can help with potential issues you may encounter but should not be viewed as a cure-all.