The powerline things work pretty well. My friend has one in his house due to a similar issue. He gets the same ping to servers as I do (we live within 20min of each other, and my rig is eth directly to my router), the only downside is for whatever reason he has trouble keeping a server up if he hosts (tends to lag). But, he does not experience any lag when he is gaming. and his computer is effectively the same as yours but intel and nvidia comparable components.
If you have a retail store that allows restocking-free returns, Id buy one and try it out. Try it for however long their return is, if it works keep it. if not, get your money back.
They cost about 150USD for a good one retail, etail is cheaper of course but returns cost you most of the time.