Thermal paste, or some oily thermal interface material, is necessary because it fills in the microscopic imperfections that otherwise trap air particles between the CPU and the heatsink, preventing the CPU from properly cooling. Heat radiates outward from the CPU to the heatsink, before eventually making its way to a fan where it disperses; but, since air is a notoriously poor conductor of heat, an outside element is needed to bridge the gap between the two components.
Typically, PC-grade thermal paste supplies the necessary bridge, but most oily household substances could temporarily suffice. A quick Internet research reveals that many users have already taken it upon themselves to test out a variety of substances for use, including vegemite, Nutella, toothpaste, and American cheese.
Jorgen Elton Nilsen, of the Norwegian tech site Tek.No, tested all of his substances using an Innovatek Kühlertester KT-3 simulator, an industry-grade heater for analyzing the cooling capacity of air and water cooling systems. Devices like Innovatek are better suited for this task, as it’s difficult to standardize the heat output of a CPU solely through software. One can’t simply activate the maximum heat output by running a 3D-rendering demo because of the inherent bias: there’s no way to determine how much of the CPU’s specified maximum power rating is used up by the software.
Instead, Nilsen set up his Innovatek Kühlertester KT-3 with a heat spreader and an Asus Triton 77 heatsink mounted on top of the CPU and proceeded to test toothpaste, yellow cheese, hair wax, moisturizing cream, butter, banana, and paper at intervals of 15 minutes under a 90-watt load.
The results will surprise you. In order from the most thermally conductive to the least:
- Butter 53.2°C
- Moisturizing cream 54°C
- Hair wax 56°C
- Banana 58°C
- Paper 67.2°C
- Yellow cheese 67.9°C
Taken at face value, it appears that the butter and the moisturizing cream are the best short-term solutions, but truthfully, both liquefied before the allotted 15-minute time frame came to a close. Considering that a motherboard sits beneath a CPU inside a computer, the liquefied oil runs the risk of spilling over onto underlying electronics.
The best solutions turned out to be hair wax and toothpaste, which exhibited a relatively low temperature without completely drying out and cracking.
If you’re impatient or under a tight deadline and need to squeeze in a few hours of extra work, consider toothpaste or hair wax when nothing else is available. When the time comes to replace it with actual thermal paste, use a sharp edge to remove the dried-up compound before applying a small amount of isopropyl alcohol to a microfiber cloth and gently scrub off any excess particles. Suffice it to say, computer-grade thermal paste eventually dries up as well, needing to be periodically cleaned off and reapplied.