You max daily OC depends on your CPU, your mobo(bios settings) and cooling system so no two are the same.
Evga X58 SLI + i7 920
My Max is 4.2Ghz for benching(will boot at 4.4Ghz but eventually crashes), 3.8Ghz during the winter months(the office is cold) and 3.6Ghz during the summer months(the office gets real hot).
I don't trust any of the temperatures people post because often the temp is dependent on what software was used to do the monitoring and can be off as much as 5 - 10C. Frankly some of the readings are pretty unbelievable.