The CPU core voltage (V_CORE) is the power supply voltage supplied to the CPU (which is a digital circuit), GPU, or other device containing a processing core. The amount of power a CPU uses, and thus the amount of heat it dissipates, is the product of this voltage and the current it draws. In modern CPUs, which are made using CMOS, the current is almost proportional to the clock speed, the CPU drawing almost no current between clock cycles. (See, however, subthreshold leakage.)