Magic smoke (also factory smoke, blue smoke, angry pixies, or the genie) is a humorous name for the caustic smoke produced by burning out electronic circuits or components (usually by overheating, overamping, or incorrect wiring configurations), which is held to contain the essence of the component's function. The smoke typically smells of burning plastic and other chemicals, and sometimes contains specks of sticky black ash. The color of the smoke depends on which component is overheating, but it is commonly white or grey. Simple overheating eventually results in component failure, but does not release smoke. Real smoke is almost always the result of incorrect wiring or a manufacturing failure in the component.
The name is a running in-joke that started among electrical engineers and technicians. It was more recently adopted by computer programmers. It is a widely used term with competitors in the FIRST Robotics Competition.  The given device operates until the smoke is released from it, at which point the device ceases to operate. Ergo, the smoke is an essential part of the device's operation, through undetermined ('magical') means. The joke's humor operates via the logical consistency of what is observed, versus knowledge of what is actually occurring. This is an example of the fallacy post hoc ergo propter hoc.
This has led to phrases (and variants of) "You let the smoke out!", "There's too many angry pixies running through the circuit!", "The magic smoke is escaping." or "I think you set your power supply too high; there is magic smoke coming from that resistor!" as euphemisms for the destruction of a component by overheating.
When a device is powered on for the first time, it is often called a "smoke test".
Tier 3 Incompatible and Unsupported CPUs
- Smokeless CPUs: Smokeless CPUs are incompatible with the linux kernel and it is doubted that any work will ever be performed to change this. They are simply too unreliable in even the most standard system configuration. Those with a CPU missing its Magic Smoke should switch to a new CPU.
The joke in the above quotation is the concept of a Smokeless CPU—one in which the vital magic smoke has been released, rendering it inoperable. The joke remained in Red Hat 6.2, but was removed in a subsequent version.
- ""Magic Smoke" came out? Here's the cure. - Chief Delphi". www.chiefdelphi.com. Retrieved 2016-10-05.
- "Magic Smoke". Retrieved February 9, 2014.
- "Red Hat, Inc. Hardware Compatibility List for Intel/6.1". Apr 19, 2000. Archived from the original on December 4, 2000. Retrieved May 19, 2013.