I am planning to upgrade my current rig with hopefully only a new gpu and an additional hardrive. Currently run MSI P55-GD65 with a core i7 870 and a 5870. What would you recommend for a gpu? Gtx 670? Will the cpu serve as a bottleneck or will it be okay?
More aboutthinking upgrade
PCIe 3.0 cards will work on PCIe 2.0 boards. Your i7 should not bottleneck. As long as you have enough headroom on your PS you should be fine.
As long as your PSU is sufficient, you can throw any card you like on that rig. Get the best card you can afford.