1) Ram, how many stick of ram do you have, Are they all similar as in brands, speed, latency?
2) If you have 2 sticks of ram, are then installed in the Tan colored Dimm slots? (if you have 4 sticks it don't matter just fill all the slots up. If you have the stick in just the black slots which can hurt performance in some games I've came a crossed on some systems, or is one stick in the tan and the other in a black stot, if so you are running in Single channel which can hurt performance quit a bit depending on the software.
3) Any overclocks on either of your system or his?
4) Mdd1963 brought up a good point, is the MCE = Multi-Core-Enhancement enabled in your bios? If you good good cooling (not the stock fan) Enable it and you'll get a boost when the CPU turbos, XMP, I would enable XMP as well.
5) Drivers? Are they updated?
6) Updates??? make sure windows is updated as well
7) Temps, check temps of the CPU and GPU, CPU I recommend you keep below 80C but it wont hurt it to go higher but still thats my limit personally, but some motherboards can start throttling at around 80C or so.
Now I don't think MCE or RAM speeds can have a huge impact in performance, the 1060 6Gb is as fast as a GTX 980, the 3GB irreverent can be a little slower but still faster then the 970. If his CPU is clocked much higher then It could performance better then your system but not that much better.