Question DC Powered ATX Motherboard

[leviself56]

I am building a DC Powered ATX Power supply to run my motherboard.
The old power supply died and I have the rest of my equipment running off of a deep cycle battery with a Samlex battery charger.
When the power goes out, everything continues to run....

So I have purchased some Meanwell DC-DC transformers (9-18Vin & 3.3Vout, 5Vout & 12Vout).

Yellows are wired to +12v
Reds are wired to +5v
Oranges are wired to +3.3v
Purple wire connected to +5v.
Gray wire is also connect to +5v (PWR_OK)
Black wires are all connected to ground of each transformer.
Blue wire is not connected (it's -12v, and from what I've read, it's only there for backwards compatibility).
Green wire is not connected (as I believe it is used for signaling the ATX PSU to power on).

I have everything wired with the correct color codes, and when connected to the motherboard, the system fan & cpu fan kicks on.
Yet nothing else happens. I do not get a POST/BIOS screen and I am not getting any status lights on ethernet port on motherboard.
Motherboard works fine when connected to a known good working PSU.

Just wondering if there as something simple I am missing.

 

[jonnyguru]

Just wondering if there as something simple I am missing.

Probably.

Try not energizing the Power Good signal.

 

[jonnyguru]

So I take it not putting +5V to the power good fixed the problem and that's why you haven't come back?

 

[leviself56]

So I take it not putting +5V to the power good fixed the problem and that's why you haven't come back?

No, actually, in my troubleshooting process, I tried not energizing the PWR_OK line, and it has the same effect.
I actually work a full time job and only have so much time to check this thread.

 

[jonnyguru]

No, actually, in my troubleshooting process, I tried not energizing the PWR_OK line, and it has the same effect.
I actually work a full time job and only have so much time to check this thread.

Interesting. What motherboard are we using here?

 

[leviself56]

Interesting. What motherboard are we using here?

Base Board Information
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: F2A88XM-D3H
Version: x.x
Serial Number: To be filled by O.E.M.
Asset Tag: To be filled by O.E.M.
Features:
Board is a hosting board
Board is replaceable
Location In Chassis: To be filled by O.E.M.
Chassis Handle: 0x0003
Type: Motherboard
Contained Object Handles: 0

 

[jonnyguru]

Ok. So it's an 8 year old motherboard, so it doesn't support modern standby modes, but it's still not so old that it needs the -12V.

One of your wires has to be connected wrong.

 

[leviself56]

Double checked all of the voltages again, and every wire is properly outputting correct voltage when measured to the black common.

With or without the gray wire connected to +5v, I get this same result:

CPU fan revs up when first applying power and holds.
If I short the pwr switch pins, CPU fan stops revving, slows down, ethernet link light turns green, but not getting any output to the display.