GeForce 7800 GTX 430 MHz + 40 MHz ?

I was discussing something with Unwinder today (Rivatuner programmer) as he has had a lot of reports of unusual core clocks for the GeForce 7800 GTX. After investigating it myself it seems that the minute you startup a 3D application, the GPU core frequency jumps towards 468 MHz (should be 430), a ~40 MHz difference is reported with any GeForce 7800 GTX. You can only measure this once you actually follow the clock real-time (see image below).