Editing Quiet PC (section)

===CPU===
The heat output of a CPU can vary according to its brand and model or, more precisely, its [[thermal design power]] (TDP). [[Intel]]'s third revision [[Pentium&nbsp;4]], using the "Prescott" core, was infamous for being one of the hottest-running CPUs on the market. By comparison, [[AMD]]'s [[Athlon]] series and the Intel [[Core&nbsp;2]] perform better at lower clock speeds and thus produce less heat.

Modern CPUs often incorporate [[Power management|energy saving systems]], such as [[Cool'n'Quiet]], [[LongHaul]], and [[SpeedStep]]. These reduce the CPU [[clock speed]] and [[core voltage]] when the processor is idle, thus reducing heat.  The heat produced by CPUs can be further reduced by [[undervolting]], [[underclocking]] or both.

Most modern mainstream and value CPUs are made with a lower [[Thermal Design Power|TDP]] to reduce heat, noise, and power consumption. Intel's dual-core [[Celeron]], [[Pentium]], and i3 CPUs generally have a [[Thermal design power|TDP]] of 35&ndash;54&nbsp;W, while the i5 and i7 are generally 64&ndash;84&nbsp;W (newer versions, such as [[Haswell (microarchitecture)|Haswell]]) or 95W (older versions, such as [[Sandy Bridge]]). Older CPUs such as the [[Core 2 Duo]] typically had a TDP of 65&nbsp;W, while the [[Core 2 Quad]] CPUs were mostly 65&ndash;95&nbsp;W. AMD's [[Athlon II x2]] CPUs were 65&nbsp;W, while the Athlon&nbsp;x4 was 95&nbsp;W. The [[AMD Phenom]] ranged from 80&nbsp;W in the x2 variant to 95 and 125&nbsp;W in the quad-core variants. The [[AMD Bulldozer]] CPUs range from 95&ndash;125&nbsp;W. [[AMD APU]]s range from 65&nbsp;W for the lower-end dual-core variants, such as the A4, to 100&nbsp;W in the higher-end quad-core variants, such as the A8. Some processors come in special low-power versions. For example, Intel's lower TDP CPUs end in T (35&nbsp;W) or S (65&nbsp;W).