As nareshkrania said , all of these cards are 6-7 years old. And they were low end cards even when they were new. A smart phone has better gpus then these now days.
If for some reason this rig isnt heading twords a trashcan the gt 520 miiiiight be a mousefart better.
But with this rig you prettymuch will have a hard time even watching youtube or hd movies.