Okay....I have an Inspiron 620 whose motherboard was fried in an electrical storm. I ordered a replacement motherboard and it is exactly identical with the same model number and appearance.
On installing, it posts as an Optiplex 390. OK, no big deal, except--
The inspiron uses a standard FrontPanel connector and this FP works perfecly, Power switch works, lights come on, system boots.
However, the Optiplex 390 has one difference--the power button for it connects to a proprietary 5-pin connector on the top corner of the motherboard.
The end result is that despite the motherboard working in every way, at boot, the system board reports ALERT: POWER BUTTON CABLE FAILURE.
Of course, this is no surprise since there is not cable attached.
Since the motherboard appear identical, I tried to flash the BIOS to the inspiron 620, but that would not work. I searched the BIOS for a way to suppress the error message. Nothing. Is there anything I can do to get rid of that message? Short two pins on the 5-pin connector? Some way to reprogram the board (force BIOS change) to think it is a Inspiron 620?
Yeah, that is what I was thinking, too. I just hope that it does not override the FP connector on/off.
I know that normally reprogramming BIOS requires special equipment, but I hoped that since the motherboards are identical it might as simple as using the BIOS flash, but no, didn't work out.
Still, I bet if we only knew which pins were for what, I could probably just short two and solve the problem.
Glad I am not the only one to have done all the above and still have the PWR button cable fail. Still looking for a solution. Otherwise after F1 to boot all is well.
I know this is an old post but I'm putting my solution here in case it can help someone in the future. I ordered a board off Amazon to replace a failed board in an Inspiron 620. It seems most of the refurbished boards that are being shipped are from OptiPlex 390 computers instead of an Inspiron. While they are physically identical, the firmware is slightly different.
I happened to have a 390 in the shop at the time so I did some investigating. The 390 power button connects in a different location than the 620. I put my meter on the cable for the 390 and found the red and yellow wires are shorted together through the switch. So, I just used a jumper to jump those two pins on the motherboard in the 620 and all is well again. See my pics for what I did.
The pictures you have posted here of a GX390 and GX620 are not accurate for the question. The question is for a OptiPlex 390 and Inspiron 620. Your bottom picture is the correct picture. The top picture is from a much older generation.
The optiplex GX620 and Inspiron 620 are completely different systems. The answer is that this isn't going to be easy.
You can easily find complete used Optiplex 390 systems for $75-100 or so - sell the board you purchased and go that route. It'll be far easier than any alternative option.
trippb, I would like to thank you for your help on fixing the "ALERT! POWER BUTTON CABLE FAILURE." , I bought an old dell optiplex 390 motherboard cheaply so I could use it to upgrade an older computer, I found the pinout to plug in the power button , the HDD LED, and the Power LED , but it appears there are additional undocumented pins on the front I/O header that are jumped together , so everytime I turn the machine on I get an annoying error "ALERT! FRONT I/O CABLE FAILURE" . I tried looking up pictures of the cable but I couldn't get a clear enough view of the connector get a complete pinout. Does anybody have the complete pinout for the front I/O cable? or maybe, trippb could you be so kind as to analyze the front I/O cable for me and tell me what pins I need to jump together so that I can trick the motherboard into thinking the the OE front I/O is connected and stop the motherboard from annoyingly and somewhat unnecessarily halting the boot process for a non-critical error.