im trying to upgrade my pc to a gaming pc need help

Solution
It looks like that power supply has a 6pin PCI-E power connector. The i7 2600 would be able to place a gtx 1060 6gb under 100% load for 1080p gaming.
The GTX 1060 6gb doesn't draw nearly as much power as the gtx 560 and should fit nicely inside your existing dell 8300, giving plenty of graphics horsepower.