In overclocking there is a constant issue of heat created by the CPU. Not only does it lower the stability of a processor as the temperature increases it also can cause damage to the CPU and lowers the tolerance to higher voltages which further causes damage. Inversely as temperatures decrease there is generally an increase of stability and a higher tolerance to voltage before true damage is done. Because of this, overclockers seeking the absolute max in performance, will resort to exotic cooling methods such as water chillers, phase change units, dry ice, and even liquid nitrogen (LN2). This can allow for lots of scaling and significantly higher clock speeds, as much as 7-7.3 GHz on the latest 9900KS with LN2. However, there is a major issue that once components are cooled below the dew point of the air, they start to accumulate condensation and eventually frost/ice if the temperatures are low enough. Properly prepping a system for subzero overclocking beforehand protects components from being shorted and destroyed by moisture.
So, what is needed for prepping a system for subzero overclocking? Well most preparation typically starts by insulating the motherboard to make it fairly waterproof using a variety of materials such as plastidip, liquid electrical tape, conformal coating, kneaded eraser, or Vaseline all with their pros and cons. Vaseline is popular as it is a fairly easy application and can usually be removed by running the motherboard through a cycle in the dishwasher. However, it is also very messy and attracts dust, not to mention it’s easy to get into sockets and slots possibly causing loss of function or stability of board if it can’t be removed. To insulate with Vaseline, you paint it on with a brush then use a hair dryer or heat gun to melt and flow it for total coverage of all expose metal that can cause a short.
Kneaded eraser is popular because just like Vaseline it is easy to remove, perhaps even more so as it tends to not get into slots meaning you can pull it all off and be done. The largest downside of kneaded eraser is it takes a lot of time and effort to completely cover a board with it and usually requires quite a bit of kneaded eraser. Application is basically just forming a layer of kneaded eraser across then entire surface of the motherboard to create a thick barrier for all moisture.
Finally, the most common method of insulation is to paint a waterproof layer on with a material like plastidip, liquid electrical tape (LET), or conformal coating. This is great because it’s fairly permanent unlike Vaseline and kneaded eraser and if you use plastidip or LET it can still be removed although it is not as easy or simple as with kneaded eraser and Vaseline. Conformal coating is basically permanent meaning that if you mess up the application it’s probably not possible to fix it. There are some issues though, LET tends to flow upwards into sockets while drying which can cause the pins inside the socket or slot to be electrically insulated and no longer work meaning you have to be very careful when applying LET around the base of memory slots and cpu sockets. While plastidip doesn’t share this problem as much due to being thicker it does have the problem of if you get it under a BGA and go to remove the plastidip you will break the solder under the BGA. If you chose to use any of these materials the application is simply masking off slots and sockets then painting it on, plastidip also comes in a spray can but you’ll need many more layers if you spray on than if you paint on. Some people also prefer to apply using a syringe and just applying to areas with exposed contacts, this does make it easier if you choose to remove the insulation later.
Once the base layer of insulation has been applied some people like to apply cut pieces of a closed cell foam such as Armaflex near the socket and will have a cut piece of closed cell foam to place their board on top of. Personally, I prefer to place my motherboard on top of a piece of foam but instead of using foam on top of the board I use blue absorptive shop towel. Typically, I cut pieces to size and shove it between mem slots and all around the socket. Then I’ll lay a piece over any components that can have pieces of frost fall onto them. I prefer shop towel as it cuts down on the amount of moisture on components by absorbing water rather than allowing water to sit on top of it.
After this is done some will use a socket heater underneath their socket which keeps the PCB warm with a heating element while the CPU is still cool, this can prevent a lot of condensation on it’s own. Another method that works well is to put everything into a purge case where all air is purged out thus preventing moisture from getting close, however that take a lot of space and can be expensive.
We’ll be playing with LN2 in our lab in the coming months, and will be sharing our findings with new hardware and the limits they can be pushed to.