The 6 and 6+2 is fine, just make sure they are all snug in each socket. You can measure the voltage with the system on. Just insert the probes carefully into the back side of each connector. If you don't have a volt/ohm meter, you might want to get one. You don't need anything professional, $25 to $40 would be fine! You can use them for home AC ( wall plugs ), cars (12v), your computer, ect... Good tool to have!