Dell OptiPlex GX280. Amber blinking light. Won't power on.

Alright, so here's the situation.

I have in my possession a Dell Optiplex GX280, that won't power on. It has the amber blinking light when the PSU is plugged in. Now at first, it seemed like the motherboard, because we took out/unplugged each individual part till it was only the motherboard, cpu, front usb/power port  (which contains the power on switch) and the power supply. So we ordered a new Mobo in.

New mobo comes, and we still have the same problem. Tried replacement PSU, and CPU (though I can't guarantee that the other CPU was compatible with this board, or working). The one oddity that I have noticed now, is that if I unplug the front usb/power port and plug in the PSU with just the mobo/cpu the fans starting kicking and the machine seems to power up. Though I have no video display what-so-ever. Tried a known good video card, and the same issue. It's only when I have the front usb/power port plugged in that the computer won't power up.

There are also no error codes displayed on the front panel. I've looked around at similar situations and unfortunately haven't found one that helps my current situation. Does anyone have a clue what could be causing this?
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madmark75Connect With a Mentor Commented:
In a few cases with Optiplex GX280's and a few other GX2XX models - the blinking amber light in my past experience with them has either been the power supply or a faulty motherboard. At that time we still had dell warranties so we received a new mobo or power supply from them and the issue was resolved. One thing to check for sure - make sure that the capacitors on the motherboards do not have corrosion or "oozze" - the "puffy" capacitor issues, especially the ones right near the back of the board where all the peripherials go if haven't ran into any articles about already.

Article here with more info about the puffy capicitors issues with Optlix PC's in case you haven't ran into anything info about that:

The front usb power is definitely an oddity, but the place to start I think would be to check both motherboards for the puffy or oozing capacitor issue since it could be related and I'm not sure where you got the replacement mobo from or know about the major issues with the capacitors already on those models. After that I can only suggest to check the Dell service manual to make sure the front USB port is plugged in properly if it doesn't boot without it unplugged.

Let me know.

- Mark
Michael-BestConnect With a Mentor Commented:
Check Hard Drive, Mem, etc:
Here a link to HDD makers Hard Drive Diagnostics Tools and Utilities
Download free and burn a boot CD on a computer with a CD burner.
Diagnotic tests for your computer.
Hit "c" (+"Alt")  during power on to boot from CD, then run in DOS.
Michael-BestConnect With a Mentor Commented:
No floppy?
Put Hard Drive Diagnostics Tools on a  a USB Flash drive
Boot from USB Flash drive
How To Boot From A USB Flash Drive
MKBT, Make Bootable
Set BIOS to boot from USB
Hit F8 (F5 on some computers) on re-boot to enter BIOS
Set BIOS to boot from USB
When done:
Set BIOS to "default"
lccjltAuthor Commented:
Turns out it was a defective cable and I/O board (usb/power switch). Thanks for the help though guys.
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