I totally agree with Andy on that core voltage- you are running it way too high for 3.6 GHz.
and RJR mentioned that VTT voltage of 1.21- I know that 1.21 would be fine for 3.6 GHz. You probably won't have to worry with that to get the 860 up to 4 GHz.
My best secret - turn off Hyper Threading. It makes a tremendous difference in temperature under load.
You most certainly can do 4.00GHz. I recently built a Core i7 860 rig with the P7P55D Pro board and i was very near that mark on stock cooling. I did massive amounts of benchmarking on it for an overclocking article. You can see the CPUz info for my final settings at http://solidlystated.com/hardware/core-i7-860-overclocking/10/
. ---This is on the stock cooling fan.
I left it at the settings from that page so I could have rock solid stability and Prime95 maximum temps of 80 degrees. In one of my earlier trials, I had the CPU @ 4GHz and the RAM at 2000 MHz. It ran fine under windows, but I had the core voltage at 1.28V and did not dare put it under full load. (At that voltage with stock cooler, it would reach shutdown temp in about 20 seconds).
I suspect that if you put a nice big aftermarket heatsink and fan on it, you can safely put that 4 GHz chip under load without baking it. Keep in mind that the Core i7 860 will never be under that much load in regular computing or gaming. Only in serious video encoding can you burden it that much.