You didnt have your pcie slot overclocked at all did you? Did you setup the pc in the first place? An overclocked pci slot may have given you a boost or more likely your fsb was sligthly higher which would allow everything to run above standard clock speeds. If your going to tinker then dont touch the pcie slot overclock though because thats a good way to kill your gpu, A slight bump on your fsb may give you a noticeable increase though.