PC Components

How Many Volts Does a Computer Use?

Computer Power Supply

A computer is a very specific piece of device. In essence, whether you are trying to build a PC or replace a part on a PC, everything about it has to be precise, or else you’d run into complications. One such thing that needs to be specific in a computer is the voltages it requires. So, how many volts does a computer use? 

Quick Answer

A computer uses switching power supplies technology to convert the AC input to a lower DC voltage. This technology’s typical voltage ranges from 3.3 to 5 or even 12 volts. The digital circuits often use 3.3 and 5 volts. At the same time, the 12 volts are used for things like the fan, RGB, disk drivers, and so on. 

While knowing the required voltage a PC requires is important, the main specification of the power supply of a PC is in watts. The watt is the product of the voltage in volts and the current in amperes. Keep reading to learn more about the use of voltage in a computer. 

How Are Volts Distributed in a Computer? 

When you plug your computer into a power outlet, the input voltage is between 220 and 110 volts of AC, depending on your region. However, a computer does not make use of an AC. Rather, it uses DC. Moreover, the voltage gotten directly from the power outlet is too high for a PC. Hence, your PC has to step down the voltage and convert the AC to DC. Computers make use of a PSU to convert the AC to DC. 

Irrespective of what OS you have on your PC, it uses a string of code called the ACPI to monitor and control the power consumption of its components. The ACPI decides where partial, full, or zero power is sent to the PC. Below is a general guide on how voltage rails.

3.3 Volts 

The 3.3 volts on a PC are the most essential in a CPU because of what they power. This voltage is required essentially by DIMMS, chipsets, cards like PCIe, AGP, and PCI, and various other miscellaneous chips. You can find both the +3.3 and -3.3 volts in a PC’s power supply. By the industry’s standardization, this voltage is often carried by the orange wire in a 235-watt ATX PSU, which can also support a maximum of 14 amps

5 Volts 

The 5 volts are also essential and are often used for powering basic things on the PC. It powers components like the chassis, CPU fan, USB ports, SIMMs, PCI, AGP, ISA, low-voltage motor, disk drive logic, and so on. In essence, the 5 volts are widely used on the PC. By standardization, this voltage is carried by the purple wires when the PC is on standby mode. But when there is activity on the PC, the red wire carries the +5 volts while the white wire carries the -5 volts

12 Volts 

Similarly, the 12 volts might be the least used voltage on the PC, but it also plays a critical role in ensuring your PC performs optimally. The 12 volts are used to power motors, high output voltage regulators, AGP, PCIe cards, and other components that require high voltage. The 12 volts feed power to the main board and graphics card in many new-generation PCs. Regarding standardization and color coding, the +12 volts are carried by the yellow wire, whereas the blue wire carries the -12 volts.   

Quick Note

Note that in the modern market, negative voltages are relatively obsolete. However, you might still need to know how to use them if you install a new power supply in an older motherboard, especially those with ISA bus slots.


Understanding a PC’s voltage requirement will help ensure you don’t exceed its limit. However, it is much better to consider the wattage when taking note of the power requirement of a PC. With the wattage, you can effectively consider the current and voltage the PC requires to work optimally. 

Frequently Asked Questions 

Does high voltage cause the PC to overheat? 

The higher the voltage a PC uses, the more power it uses. And when more power is passed through a PC, it causes the temperature to rise. To protect the PC’s components, you need to install a more sophisticated cooling system if you intend to operate the PC on high voltage or overclocked. 

How do I check the power supply voltages? 

Generally, the easiest way to know a PC’s voltage is by following the colored coding. However, another way is by using a voltmeter or a multimeter. And if perhaps the PC is on, software like AIDA64, HWiNFO, and so on, which you can use, will provide you with vital information about the PC, including the voltage. 

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