Q: ATX Motherboards with 3.3V on 5V PCI Slots

[Michael Gillies <mgillies@dgs.monash.edu.au>]

Hello all.

I am currently developing a PCI card with 5V and 3.3V components. I am
looking for an ATX motherboard (IBM compat./Pentium) with 5V slots that
have the 3.3V "pins" connected (directly) to the ATX power supply. I am
assuming that the 3.3V from the ATX power supply feeds directly to the
3.3V pins on the PCI slots because the maximum current output is in the
order of 14A to 16A and the 3.3V components on the motherboard could not
(possibly?) use this much power.

The obvious option is to place a 3.3V regulator on the card (there is
room for one), but I would still like to have a motherboard with a
suitable 3.3V supply to the PCI slots. My card is for research purposes
only and is not intended for commercial use. In its current state, the
card will only be used in my PC. By drawing the 3.3V power directly from
the motherboard, it could be said that my card is non-compliant. I am
not ignoring this fact, but it is not a major issue regarding my card at
this stage of development.


Thanks in advance.

Michael Gillies
mgillies@dgs.monash.edu.au