I couldn't imagine you would lose out too much. I don't really play around with the automated performance settings (like in my BIOS for the Gigabyte MoBo, I have turbo settings for the VPU, but it gives warnings (not in very good english however) that playing around might wreck your hardware!!) coz I just can't afford for anything to go wrong.
You would be surprised at the amount of things you can tweak before you need to actually adjust timings/voltages etc. I would look for an nVidia Tweak Guide. www.TweakGuides.com released one for the ATI Catalyst which worked a treat, and may also have one for the nVidia (not sure what software you use).
But either way, give the driver refresh a go, and if you still have dramas, turn down your settings.