Bundled Thermal Solutions for LGA 2011
The new 4 corner screw on mounting design for the LGA 2011 socket does away with the dodgy push-pins and should help improve mounting pressure significantly. Unfortunately we can't say anything good about the 3960X's bundled Asetek OEM water cooler for heavy overclocking (4.5Ghz on 1.4v should be achievable) – we found the pump and the fan to be lacking in cooling dexterity even at full speeds.
The TJMax of the chip is 91 degrees celcius, so you will want to keep load temperatures below that to avoid degrading your chip.
Based on our time with the 3960X, you will need a high end air cooler with a strong push-pull dual fan setup like the Thermalright Archon or Thermaltake Frio Advanced for voltages up to 1.5v (which should take you around 4.6-4.8Ghz without throttling). For extreme voltages and frequencies beyond that, a multi-radiator water cooling setup or even LN2/Helium is mandatory, which could be tricky as LGA 2011 mounting brackets are still not prevalent. Fortunately the very overclocker friendly Asus ROG Rampage IV Extreme gets around it with X-Socket.
Optimal Temperature Range for LN2 clocking
Our hardcore friends from the ASUS ROG team have put their chips and boards under extreme cooling, and found -60 to -70 degrees celcius to be the most optimum operating temperature for the maximal cpu frequency overclock.