the processor will not function correctly, although undervolting too far does not typically lead to permanent hardware damage (unlike overvolting). Undervolting is used for quiet systems, as less cooling is needed because of the reduction of heat production, allowing noisy fans to be omitted. It is also used when battery charge life must be maximized. Chip-integrated Conventional cooling techniques all attach their "cooling" component to the outside of the computer chip package. This "attaching" technique will always exhibit some thermal resistance, reducing its effectiveness. The heat can be more efficiently and quickly removed by directly cooling the local hot spots of the chip, within the package. At these locations, power dissipation of over 300 W/cm2 (typical CPU is less than 100 W/cm2) can occur, although future systems are expected to exceed 1000 W/cm2. This form of local cooling is essential to developing high power density chips. This ideology has led to the investigation of integrating cooling elements into the computer chip. Currently there are two techniques: micro-channel heatsinks, and jet impingement cooling. In micro-channel heatsinks, channels are fabricated into the silicon chip (CPU), and coolant is pumped through them. The channels are designed with very large surface area which results in large heat transfers. Heat dissipation of 3000 W/cm2 has been reported with this technique. The heat dissipation can be further increased if two-phase flow cooling is applied. Unfortunately, the system requires large pressure drops, due to the small channels, and the heat flux is lower with dielectric coolants used in electronic cooling. Another local chip cooling technique is jet impingement cooling. In this technique, a coolant is flowed through a small orifice to form a jet. The jet is directed toward the surface of the CPU chip, and can effectively remove large heat fluxes. Heat dissipation of over 1000 W/cm2 has been reported. The system can be operated at lower pressure in comparison to the micro-channel method. The heat transfer can be further increased using two-phase flow cooling and by integrating return flow channels (hybrid between micro-channel heatsinks and jet impingement cooling). Phase-change cooling Phase-change cooling is an extremely effective way to cool the processor. A vapor compression phase-change cooler is a unit that usually sits underneath the PC, with a tube leading to the processor. Inside the unit is a compressor of the same type as in an air conditioner. The compressor compresses a gas (or mixture of