My parents have an old Inspiron 580 with a Core i3 550 and I wanted to upgrade it to Windows 10 since Windows 7 is inching closer to end of life. When I tried to upgrade, it told me whatever version of Intel HD Graphics onboard wasn't supported and wouldn't install. I ordered an old Nvidia GTX 650 for $30 off eBay to modernize graphics (DirectX 9 is minimum spec for Windows 10), and figured I might as well upgrade to a quad core CPU while I'm in there, but I can't tell what's supported on the Inspiron 580 support page, just says "Intel Core i3 and Core i5" in the PDF of the manual. 

Socket LGA 1156 is compatible with the i5-760, and I found one on eBay for $11, but figured it'd be smart to double check before buying.