Rebuild. That PSU is not good and no point upgrading in that system because you will be handicapped. The below build is below $1.3k.
PCPartPicker part list:
https://pcpartpicker.com/list/DPY7P3
Price breakdown by merchant: https://pcpartpicker.com/list/DPY7P3/by_merchant/
CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor ($178.65 @ OutletPC)
Motherboard: MSI - Z370-A PRO ATX LGA1151 Motherboard ($117.89 @ OutletPC)
Memory: G.Skill - Aegis 16GB (2 x 8GB) DDR4-3000 Memory ($167.99 @ Newegg)
Storage: SanDisk - SSD PLUS 240GB 2.5" Solid State Drive ($69.99 @ Adorama)
Storage: Western Digital - Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($46.49 @ OutletPC)
Video Card: EVGA - GeForce GTX 1060 6GB 6GB GAMING Video Card ($379.79 @ OutletPC)
Case: NZXT - S340 (Black) ATX Mid Tower Case ($59.99 @ Newegg)
Power Supply: Corsair - RMx 650W 80+ Gold Certified Fully-Modular ATX Power Supply ($89.99 @ Newegg)
Operating System: Microsoft - Windows 10 Home OEM 64-bit ($89.89 @ OutletPC)
Total: $1200.67
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-02-28 22:51 EST-0500