Hello,
Do you have your 4 or 6 or even 8 pin connector plugged in? That's the most likely case here.
This is an old build (Sandy Bridge) With the 2nd Gen i5. The bottleneck here is also to consider, You have a 1060 3GB With a 2011 CPU. My recommendation is to downgrade 1060 to 760/770/1050/670 and 670ti.
Your best bet here would be 1050 (Not the 1050ti), Or if downgrade isnt an option you can upgrade the processor to an i7-2XXX or i7-3XXX and potentially i7-4XXX But for 4th gen you probably would have to swap the motherboard as 2nd and 3rd gen Intel processors have the socket LGA 1155, Intel 4th gen have LGA 1150, But you could upgrade your 2nd gen i5 to 3rd gen. If you do make those upgrades/downgrades you should probably upgrade your PSU if you do Upgrades.
Feel free to start a conversation with me if you have questions.,
Kuba