Power Supply Voltage Tolerances GA S REGULAR Menu Lifewire Tech for Humans Newsletter! Search Close GO Computers, Laptops & Tablets > Accessories & Hardware 164 164 people found this article helpful

Power Supply Voltage Tolerances

Proper voltage ranges for ATX power supply voltage rails

By Tim Fisher Tim Fisher Senior Vice President & Group General Manager, Tech & Sustainability Emporia State University Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the VP and General Manager of Lifewire. lifewire's editorial guidelines Updated on August 29, 2022 Tweet Share Email Tweet Share Email Accessories & Hardware The Quick Guide to Webcams Keyboards & Mice Monitors Cards HDD & SSD Printers & Scanners Raspberry Pi The power supply in a PC supplies various voltages to internal devices in a computer through power connectors. These voltages don't have to be exact, but they can only vary up or down by a certain amount, called a tolerance. If a power supply is providing the parts of a computer with a particular voltage outside this tolerance, the devices being powered may not work properly—or at all. Below is a table listing the tolerances for each power supply voltage rail according to Version 2.2 of the ATX Specification (PDF). Thermaltake Dr. Power II Automated Power Supply Tester. Thermaltake

Power Supply Voltage Tolerances ATX v2 2

PSU Tolerance Table Voltage Rail Tolerance Minimum Voltage Maximum Voltage +3.3VDC ± 5% +3.135 VDC +3.465 VDC +5VDC ± 5% +4.750 VDC +5.250 VDC +5VSB ± 5% +4.750 VDC +5.250 VDC -5VDC (if used) ± 10% -4.500 VDC -5.500 VDC +12VDC ± 5% +11.400 VDC +12.600 VDC -12VDC ± 10% -10.800 VDC - 13.200 VDC To help when testing a power supply, we've also calculated the minimum and maximum voltages using the tolerances listed. You can reference our ATX Power Supply Pinout Tables list for details on which power connector pins supply which voltage. Power Good Delay is the amount of time it takes a power supply to start up completely and begin delivering the proper voltages to the connected devices. According to the Desktop Platform Form Factors Power Supply Guide [PDF], Power Good Delay (called PWR_OK delay in that document) should be 100–500 ms.
Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit More from Lifewire How to Manually Test a Power Supply With a Multimeter 4-pin Floppy Drive Power Connector Pinout How to Use a Power Supply Tester to Test a PSU 4-pin Peripheral Power Connector Pinout 24-pin Motherboard Power Connector Pinout 15-Pin SATA Power Connector Pinout ATX Power Supply Pinout Tables What is a PSU? What is an ATX Power Supply? How to Install a Desktop Power Supply What Is a PATA Cable or Connector? How to Fix a Computer That Turns on but Displays Nothing ATX 6-pin Motherboard Power Connector Pinout How to Fix a Computer That Turns On and Then Off 4-pin Motherboard Power Connector Pinout How to Reseat Internal Data and Power Cables How to Fix a Computer That Shows No Sign of Power Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up Newsletter Sign Up By clicking “Accept All Cookies”, you agree to the storing of cookies on your device to enhance site navigation, analyze site usage, and assist in our marketing efforts. Cookies Settings Accept All Cookies