To properly answer how long computer power supplies last, we need to break things down a little into individual components. This will enable me to give you a complete answer to the question.
Although most people tend to use power supplies to the very end and only replace them once they stop working, I’d like to encourage everyone to take action earlier to increase the chances of your computer working reliably for longer.
A computer power supply should be changed after five years. After this time, a power supply will most likely become less efficient and possibly cause a system to become unstable. The primary causes are aged capacitors and other components, power surges, heat, and other mechanical stresses.
With that very general rule of thumb out of the way, premium brands like Seasonic make power supplies that can last ten years or more.
Now that we have a general guideline about the lifespan of a power supply let’s break things down further to paint a complete picture by looking at individual components that make up a power supply.
Note: The age of components discussed in this article is dealt with in actual running time, not shelf life.
What is a power supply?
A power supply is one of the main components of a computer that takes power from the wall socket and converts it from AC to a usable DC voltage which usually consists of a +12 Volt, +5 Volt, 3.3 Volt, and in older power supplies, a -12 Volt and -5 Volt outputs.
The motherboard, other internal components, and computer case use each type of voltage for various subcomponents.
A laptop doesn’t have a fully dedicated power supply like a desktop machine, but it does need one to supply a DC voltage in order to charge the internal battery.
The lifespan of individual internal components of a power supply
Like any electronic device, power supplies are made up of a circuit board with components assembled and soldered onto it.
More unique to a power supply, you also find a cooling fan to keep components cool within the power supply’s metal case.
This is probably one of the most common components that cause electronic faults just like semiconductors. As these components age, the capacitance value alters, thus changing the efficiency at which your power supply works, compared with its original design.
The most commonly used capacitor in power supplies is known as an aluminum electrolytic capacitor. These types of capacitors are made of pure aluminum foil with aluminum oxide as a dielectric.
The expected lifespan of an electrolytic capacitor is a complicated question to answer. But once the electrolytes start evaporating past a certain point, the capacitor can no longer deliver the intended capacitance value.
Computer power supplies work hard, especially for gamers or other industry work that causes the computer to work hard for extended periods of time.
This means that the temperature that capacitors operate at, is going to be more likely higher compared to ordinary applications.
So I would tend to lean toward the notion that the lifespan would be shorter than the average 10 to 20 year period.
When capacitor’s values start deviating, other components like semiconductors and resistors can be at risk of running hotter depending on the circuit’s design. Thus lowering the life expectancy of them.
The common carbon resistor is another component that can alter in value as it ages. With the heat exchange from electrical to thermal (as by its very nature), resistors can slowly start to increase in value.
This increase typically does not have a negative impact as a capacitor’s but can still offer irregularities that can cause computer components with a starved supply to point out just one example.
When a resistor’s power rating is too low for the task at hand, this degrading effect can be accelerated. This sometimes happens when circuits are designed and a value isn’t chosen properly, thus setting the component up for a shorter lifespan.
Coils, inductors, and transformers
Generally, these are some of the most reliable components you will find inside a power supply. While it’s true, I have come across plenty of faulty transformers in my time, and it is generally due to a poor design that leads to failure.
Coils, inductors, and transformers are basically enamel coated copper wires wrapped around plastic, ferrite, or magnetic core. Some inductors wound with thicker gauge wire can be manufactured and soldered into the PCB without a core.
These are not the most likely components that will cause a computer’s power supply to fail unless something has physically damaged them.
Integrated circuits have varying lifespans. This is due to a vast number of reasons. Essentially, it depends on how hot the component gets over time as to how long you can expect it to last.
Sometimes, due to poor manufacturing standards, a component like this can last for a short term period.
Reputable manufacturers for IC’s do help the overall cause, but won’t be the only thing indicating its lifespan.
Factors like the circuit’s design as to how good the smoothing of a supply line is, or how constant a voltage supply line remains under various conditions, or how much load the IC has to deal with all contribute to the lifespan of an integrated circuit.
Under the right conditions, IC’s can last for a very long time.
Other semiconductors like MOSFET’s, transistors, diodes, and voltage regulators play a crucial role in a computer’s power supply’s lifespan.
Voltages must be stable throughout the power supply, helping components receive the proper intended voltages that they require.
Regulators are components that take supply voltages and output a fixed voltage specified by the component’s value.
And semiconductors like MOSFET’s and transistors do a lot of the work when it comes to power regulation with larger currents.
Over time, with many heating and cooling cycles, these components start losing efficiency and can produce current leakages.
Once a cooling fan stops working in a power supply, the lifespan of it will be considerably shorter.
Sometimes, when fans get old, the bearing inside can cease up. Causing the fan not to spin at all, or to spin very slowly.
Of course, this is the worst-case scenario, and quite often, fans become noisy and draw more power as they age.
But if the fan slows down enough, cooling can be compromised for the power supply.
The average lifespan of a cooling fan is around 30000 hours, or 3 and a half years.
As you can see, many variables come into play when trying to determine how long computer power supplies can last.
Given that some components are so unpredictable, a specific age is very difficult to try and pin point.
At five years, some components like capacitors will start to degrade, and they won’t be doing their job as well as originally intended.
Efficiency will be affected and while the power supply may run just fine, the average user won’t be aware of the smaller impacts affecting the system.
More serious symptoms of an old power supply may include freezing, spontaneous restarts or shutdowns.
Given the negligible price of a computer power supply in most computers, it seems a very prudent decision to simply replace it with a new one.