Hardware Reference
In-Depth Information
specifications). Plugging a power supply with an incompatible pinout into a motherboard that uses a
standard pinout (or vice versa) usually results in the destruction of either the board or the power
supply—or both.
Just as I insist on industry-standard mechanical form factors in my systems, I also want to ensure that
they use industry-standard connectors and pinouts. By only purchasing components that conform to
industry standards, I can ensure the greatest flexibility and lowest cost for future upgrades and
repairs.
Two main sets of motherboard power connectors have been used over the years: what I would call
AT/LPX type and the ATX type. Each of these has minor variations; for example, the ATX type has
evolved over the years, with new connectors coming (and some going) and modifications to existing
connectors. This section details the motherboard power connectors used by various types of industry-
standard (and some not-so-standard) power supplies.
AT/LPX Power Supply Connectors
Industry-standard PC, XT, AT, Baby-AT, and LPX motherboards use the same type of main power
supply connectors. AT/LPX power supplies feature two main power connectors (P8 and P9), each
with six pins that attach the power supply to the motherboard. The terminals used in these connectors
are rated to handle up to 5 amps at up to 250V (even though the maximum used in a PC is +12V).
These two connectors are shown in
Figure 18.19
.
Figure 18.19. AT/LPX main P8/P9 (also called P1/P2) power connectors, side and terminal end
view.
All AT/LPX power supplies that use the P8 and P9 connectors have them installed end to end so that
