ATX Power Connector, Motherboard.. Needs -5V, -12V?

[Jon.boston]

I'm looking to power a PC motherboard (Via mini-itx, M10000) with an
external DC-DC based power supply. I can provide 12V, 5V, 3.3V and
5VBB but don't have -5V and -12V. Do you know if motherboards
required these voltages in general?

Thanks,
Jon

 

[Dr. Anton T. Squeegee]

In article <55beeac5.0403070538.60d0f055@posting.google.com>,
jonspam@earthlink.net says...

I'm looking to power a PC motherboard (Via mini-itx, M10000) with an
external DC-DC based power supply. I can provide 12V, 5V, 3.3V and
5VBB but don't have -5V and -12V. Do you know if motherboards
required these voltages in general?

Yes. -12 is used for the serial ports (remember that RS232 uses
bipolar signaling). -5 was, at one time, used for memory stuff, but I
don't know if it's required any more.

I would also point out two other things. First, what you're
attempting has already been done, many times, by companies who supply
parts for industrial computers. If you need a DC-DC supply for a PC, it
can be had for about $200.

Second: My attitude towards a design like this would be "Don't
leave out ANY voltage, even if it is rarely used."

In other words, if you're bent on doing this, design in both -5
and -12. Why deviate from long-established industry practice?

Keep the peace(es).


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"