If you can find another Sandy Bridge i3 or i5, then yeah you could, or an Ivy Bridge CPU after a BIOS update (do at your own risk)
Either way, at your resolution you should be fine, just make sure your PSU is sufficient as I mentioned
(Just make sure your PSU has over 20A on the +12v rail (look inside at the PSU sticker) and that it has a 6 pin PCI-E connector
If you have enough amps but no connector, you'd need an adapter)