Although this is a bit of a strange subject; it is nevertheless something which I’ve been mulling over in my mind for a number of years.

When a computer is booted up after a significant period of time since it was last used; it and all of its parts are , at that infinitessimately  (Did I spell that right?) minute moment in time, operating at room temperature: -

So yes; in essence a computer does need to “warm up”: The result of electricity flowing through its parts, causing the millions of microscopic transistors to switch at incredibly high-frequencies is heat. – That heat has to go somewhere, and it does: It flows through the individual component’s casing and most of it is caught by any type of heatsink/cooler attached to the component and radiated into the air inside the case, to be extracted from said case by a case fan.

-The question is: How long does it take for a computer to warm up?

By asking that question, I am, in reality, asking “How long does it take for the active and inactive sub-components; by which I mean the individual transistors within an integrated circuit or “chip”, as well as the passive components such as resistors, capacitors, and inductors, to reach their optimal operating temperature? What I’m not asking is “How long does it take for the entire computer or the major components of a computer to get as hot as they normally do.”

You see; by the time everything is hot inside a computer, it means the heat from the operations of the individual transistors and the electricity passing through them has permeated the casing of the component of which they are a sub-component. For instance; in a situation where the upper surface of an in-use soldered-in component consisting of thousands of transistors in a package; such as the SATA controller chip, gets hot to the touch, the actual working components of that chip have become hot and reached their thermal maximum comparatively long before the heat permeated through the chip’s casing.

- So the working transistors become hot long before the heat is actually noticeable by the observer. What about the passive components? ‘Much the same: Although they don’t actually actively switch the electricity, they nevertheless do have electricity flowing into and/or through them; which produces heat.

While it is true that the cumulative heat from an individual component plus any effects from nearby components would cause the temperature of an individual component to rise slightly beyond the thermal effect caused by the operations within; the overall effect is a uniform distribution of heat due to the design of the motherboard, and thus we can basically discount this for the purposes of this article.

Why write this article?

When I was at college, my tutor was around retirement age, and although a fully-qualified and experienced electronics engineer, he grew up in the days of valves. (Vacuum-tubes.) He used to allow his computer to “warm up” before using it. He said that it takes a few minutes to reach its working temperature. I didn’t dispute this at the time; nevertheless I do now to some extent.

Valves are a totally different commodity to transistors; even though their operation is similar; at least to some degree: Whereas the flow of current between collector and emitter, or source and drain, in a transistor, is regulated by a voltage on the base or gate; the flow of current between anode and cathode in a valve is regulated by a grid, or series of grids. There ends the similarity.

Valves need to be hot, and for all their sub-components to reach a thermal equilibrium within their glass envelope before they can work optimally, partially due to their massive size in comparison with that of a transistor. (This is achieved by what is known as a heater: It’s a heating element powered by a separate, usually AC, voltage, which is wound inside the cathode at the centre of the valve itself, and it literally heats the cathode to a point where any surplus electrons applied to it fly off into the vacuum contained within the valve’s glass envelope, being regulated by the grid on the way, and hitting the anode. To achieve this effect the voltage potential between cathode and anode must be in the hundreds of volts.) Transistors, on the other hand, work straight away. Heat is not needed; but is nevertheless produced by their operation.

- So valves; especially in the case of audio valves, need to warm up before they reach their full potential. if you ever have listened to or you ever get the chance to listen to the sound output from a valve amplifier, you’ll notice that the fidelity of the sound changes with time: The more time goes by the less the change, as the valve(s) gets nearer maximum operating temperature and it/their electrical characteristics change as a result.

The same is true, to a very limited extent, with transistors; but it’s hardly noticeable as it happens so fast: Mainly within a fraction of a second, and tails off within the first couple of seconds. Why? Because a transistor is minute compared to a valve, and therefore it heats up and reaches maximum operating temperature much faster. Also it needs no assistance from a separate heater to begin working: It just works, and any change in its electrical characteristics  due to heat occurs almost instantaneously.

To summarise…

In answer to the original question, then, I would say that a computer does need to warm up; but only for a couple of seconds at most. By the time the BIOS has kicked in, all the active components (transistors and diodes mainly.) have reached their optimum thermal state. By the time the BIOS has finished its initial work, after switching on, and the operating system’s ready to start loading up, even the passive components (Resistors, capacitors, and inductors mainly.) have likewise reached their potential operating temperature.

What do you think? Do you agree or disagree? Have you anything to add? Please do comment below. – I’m very much open to debate on this subject.