I need help deciding on what to upgrade. I only have $400
My specs are
Gigabyte ga-b250m-ds3h
i5-6600k
Corsair vengeance ddr4 2x4gb
Corsair vengeance ddr4 1x8gb
ZOTAC Nvidia Geforce GTX 1080 8GB
AMP Edition
PowerSpec 550 Watt 80 Plus Bronze
Corsair c70 case.