Hmm, not that headroom for overclocking... But you can overclock your cpu a little bit. Just do not go over 80°C with your CPU under load. Everything below is okay.
Do you just want to model with much ploygons or less? If you want to model REALLY high polygone models this isnt enough but your build should do everything you need.
If your driver decreased your performance in games, you should update because it could be a bug and I think they should have fixed it now. If you update you should get a performance boost.
Try other Headers on your motherboard or call the support for halp if there is a problem with your board. Look into the Bios! Do it say more than "error"? Is one of your Header shorted?
If your CPU is running that hot, you should look that your CPU cooler is properly build in and your cooler didn't bend over the time your PC is running. That happened to mine PC.