In the past, some laptops have used a desktop processor instead of the laptop version and have had high performance gains at the cost of greater weight, heat, and limited battery life, but the practice was largely extinct as of 2013. Unlike their desktop counterparts, laptop CPUs are nearly impossible to overclock. A thermal operating mode of laptops is very close to its limits and there is almost no headroom for an overclocking–related operating temperature increase. The possibility of improving a cooling system of a laptop to allow overclocking is extremely difficult to implement.