Optiplex 745 BIOS POST failure[s]

This problem is associated with a Dell "Optiplex 745" running Windows Vista

The BIOS is: AMI 8.06 mode VEFI

Initial indications of the problem were [in order]:

A. Unattended random power on/off cycling

B. Random "no signal" messages on monitor

C. Occasionally a successful, short-lived boot to desktop could be achieved

Since I still had occasional access to the Setup program, I ensured all settings were correct, replaced the Battery and reset the clock

Subsequent actitity:

A. Partial POST runs with message: "memory not properly identified or being used - run F2 Setup"

B. No POST advance to point of getting video to the monitor

C. Hopeful attempts to "blindly" use F2 key are unsuccessful

Prior to further troubleshooting steps,  the diagnostic light/sound pattern is:  "1" green diagnostic light followed by a 1-3-2 beep sequence [this is the current status]!!

I went to the DELL Community Support site, searched for the light/beep information and was led to several "solutions" - the most relative being this:

Excerpt from DELL COMMUNITY item of 05-16-2011

......you've arrived at the point of having to return to 1975-style diagnostics and strip down the system. First unplug EVERY cord going into the system, including power, mouse, keyboard, network cable, any and all USB devices. Open the case and remove all expansion cards and all RAM sticks. Disconnect the power connectors and the cables from ALL drives

—floppy drive, hard drive, optical drive, media card reader if you got one of them. The goal is to arrive at a point where the only things left inside the box are the power supply, motherboard, and processor.

Once you're at that point, reconnect ONLY the power cord and turn the power on. The system should respond with a series of loud beeps, grouped 1-3-2, and show "1" on the front diagnostic lights. Next, power off and reinstall the RAM sticks, one at a time for preference, and restart. You should get "23" on the diag lights, meaning all the disk drives are missing (and so they are, since you unhooked them.)

Power off again, and connect the monitor to the computer (if this means you need to reinstall the video card, do that as well). Restart, and again you should get "23" on the diag lights as well as a message on the monitor about all the drives missing.

Power off, hook up the mouse and keyboard, and ONLY the floppy drive power and data cables. Restart, and you ought to get a message on the screen about "missing hard disk," which is normal. Next, power off, leave the floppy hooked up and repeat the process reconnecting the CD/DVD drive. On restart, it should complain again because it can't find a hard disk. Power off again, reconnect the hard drive, and restart. THIS time it ought to boot.

After that, reinstall any other expansion card that may be present one at a time, attach external devices one at a time and restart after each to see whether any of them are hanging the boot. If at ANY point during the system strip and rebuild the wheels come off, and you get a result other than what I described, make a note of the diag light codes and any onscreen messages, and call tech support.

SO I DID THE FOLLOWING:

1. Disconnected/removed Unplugged ALL devices internal/external including the four RAM sticks.

2. Reset the CMOS by temporarily using the Password jumper

3. At turn-on, the power light persistently goes steady green, the POST "initiates" displaying the "1" green diagnostic light followed by the 1-3-2 beep sequence.

In other words, I'm back to where I began!! I thought I'd post this forum request before either replacing the mother board or otherwise trashing the computer.

YOUR ADVICE AND ASSISTANCE IS MORE THAN WELCOME