Weird motherboard problem - Supermicro P4SCT+II

Weird motherboard problem
I got a Supermicro P4SCT+II in trade. I put it together on my test table with a 3.2ghz P4 Northwood with a stock Intel HS/Fan and 2x1gb DDR400 Crucial memory. It powers up as soon as I turn on the power supply WITHOUT shorting the power ON/OFF pins. I figured ya, I've seen that before so I kind of ignored it. But it would not power off either by shorting the power ON/OFF pins (CPU fan keeps running). I decided to hook up a CD-ROM and a hard drive to see if it works otherwise. It installed Win XP Pro fine. Installed all the drivers fine. No problems. It works great. So I shut down Windows and it APPEARS to shut down OK (monitor turns off) but the CPU fan is still running. Then I hit the eject button on the CD-ROM and it ejects the Windows XP CD. The setup is still powered up! Just the monitor is off. I short the power ON/OFF pins. Nothing happens. Flip the on/off switch on the power supply to off and everything shuts down, of course. Flip the switch on the power supply switch to on and the board turns on and loads Windows.
So I have a board that works great but has an ON/OFF problem.
Things I have tried:
Different CPU/different HS/Fan/different memory/different memory slots/different power supply/flashed motherboard to the newest BIOS/tried different ACPI power schemes in the BIOS (it has for options: S1/S3/S1+S3 for options)/I even disabled ACPI and reinstalled Windows with the F7 option. Right now the Computer properties in the Device Manager is MPS Multiprocessor PC. So when you shut down it says It is now safe to turn off your computer. But it will not shut off by shorting the power ON/OFF pins. The monitor stays on/CPU fan is still running/CD-ROM ejects. Only way to shut it all off is flip the switch on the power supply.

Anyone have any ideas? I really would like to use this board as a home server. It has 6 SATA ports and would run a bunch of hard drives.

its possible the BIOS revision is not compatible with the CPU installed, giving strange results...??

Seems four repairable issues

1. Check your power management settings in BIOS. << Power-ON after power loss. Can turn on board when power supply plugged in.
2. Check your power management settings in Windows. << Yours did it without any O/S or hard drive even. So n0t your problem likely.
3. Does your keyboard have a power management key that may have accidently been pushed? << Maybe?? Don't know your keyboard.
4. A dead motherboard battery that supplies the BIOS when the computer is switched off, would set the pc to turn on without the pushbutton pressed but whenever the power plug is fitted into the wall socket. << Might be your problem.

After those it is usually a motherboard problem and general user cannot repair.

BIOS is set to Power Off after power loss. Board has a brand new battery in it. It did it with the Rev 1.1 BIOS that was in it originally and still does it with the latest BIOS 1.2b I flashed it to.

You know, it could be a faulty power supply... If you have another one just try it, I bet the problem goes away... Many moons ago, I had a very similar problem with my AMD 3500+ board. I would shut it down, and then it would power right back up again. I changed the power supply and the problem went away...

Solved by a member on another forum...

jkerr2 wrote:The motherboard manual seams to indicate that there is a jumper jp20. That forces power on. If the manual is correct the jumper is close to the main atx power connector. Open is disabled.

BINGO!!! jkerr2 just nailed it! Give that man a cigar. That is what was wrong. Took the jumper off the 2 pins on jp20 and everything works fantastic now! Thanks so much, I completely overlooked that.

PROBLEM SOLVED!

Interesting, I never knew that was an option, but then again, it a supermicro board.