nVidia drivers - an observation

Around F19 or F20 my old nVidia card died. I replaced it with a GeForce GTX 660 but did bother (think) to update the nVidia driver so I've been running the 304xx drivers along with my GeForce GTX 660 card just fine with KDE as my desktop. F22 came along which brought Plasma-5 to KDE. I started to have problems that I attributed to Plasma-5. After some time artifacts would appear in systray and popup areas of the systray when the mouse hovered over a process. Also at least once a day I'd lose everything on the systray and have to restart plasma. This past Saturday I decided to move to the 340xx drivers, yes I know I really should have moved to 352 now, since that is what my faulty memory told me to do. Anyway, the artifacts haven't reappeared and the systray hasn't crashed in the past 2 days. Additionally another problem seems to no longer exist. Previously when I closed the chrome browser several chrome process would be left running. With the "new" drivers this is not the case.