The primary differences between AT and ATX power supplies lie in their design, form factor, and features. Here's a breakdown:
AT Power Supply:
Design: AT (Advanced Technology) power supplies were the standard for PCs in the 1980s and early 1990s. They used a single 20-pin connector for the motherboard's power supply.
Form Factor: AT power supplies are larger and less efficient compared to modern power supplies. They typically have a size of around 5.9" (width) x 3.4" (height) x 5.5" (depth).
Switch: AT power supplies usually have a physical on/off switch directly on the power supply unit.
Wiring: AT power supplies had fewer connectors and generally lower power output compared to modern power supplies.
ATX Power Supply:
Design: ATX (Advanced Technology Extended) power supplies were introduced in the mid-1990s and became the standard for PCs. They use a 20 or 24-pin connector for the motherboard's power supply.
Form Factor: ATX power supplies are more compact and efficient compared to AT power supplies. They adhere to specific form factors like ATX, microATX, and mini-ITX, with standardized dimensions.
Switch: ATX power supplies typically do not have a physical on/off switch on the power supply unit itself. Instead, the power supply is controlled by the motherboard's power button.
Wiring: ATX power supplies feature more connectors, including additional 4-pin or 8-pin CPU power connectors, SATA power connectors for modern hard drives and SSDs, PCIe power connectors for graphics cards, and more.
Features: ATX power supplies often include features such as active power factor correction (PFC), which helps improve efficiency and reduce harmonic distortion.
Compatibility: ATX power supplies are more compatible with modern motherboards and components, offering better support for newer technologies and higher power requirements.
In summary, ATX power supplies are more compact, efficient, and feature-rich compared to the older AT power supplies. They are the standard choice for modern PC builds due to their compatibility with current hardware and improved efficiency.
