The 3.3V has been used exclusively to power PCI slots - while on-board internal regulator usually makes 3.3V for chipset and CPU, it may be too weak for some PCI boards so in early mainboards it is not routed to slots. Intel Advanced/AS mainboard), the pinout stays the same as shown in the document.

Atlantis Socket 5 and similar Socket 7 mainboards). P10 AT aux power supply connector (found on some Dell socket 5, 7 and 8 motherboards). The proprietary 3.3V connector is not only for Dell, but also IBM (especially Power Series) and Intel (e.g. Models are available for download on Ultra Librarian, or from participating distributors, manufacturers, or PCB design tools. The two negative rails are bias supplies which only have to provide small amounts of current. Download components for free in over 30 CAD formats. That was used primarily to run disk drives, motors, and fans. There are three or four lines dedicated to the 5 volt rail. As a result the PSU delivers most of its wattage at 5 volts. In old PCs, almost all of the chips ran directly off of the 5 volt rail.

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