kingston hyperx fury 8gb ram 1 stick will be good for for My Asus A68HM-K motherboard or i have to buy 2 sticks of 4gb? That will make any diffrence? My APU is AMD A8 5500
2 sticks are more powerful than one stick because they will be in dual channel meaning that they will have twice the memory bandwidth as with only 1 dimm. I would go for 2 unless you plan on upgrading to 16gb of ram.
Hope this helped