760, dead, green LED error code 3

Question

Hi All, My Optiplex 760 does not turn on. When I press the power button, a green 3 LED light comes on. It disappears when I let go of the power button.It seems a 3 means it's a possible motherboard error. Nothing on the mother board looks abnormal. No burnt smell. The amber light is on when the power is plugged in.I tried disconnecting all USB-connected devices, and even the monitor, then I pressed the diagnostic button on the back of the PSU and the green light comes on. Does this confirm that the prob is the motherboard? Should I still bother to disconnect and check the different memories and cards one by one?In the days prior to the computer dying I did get some warning signs. For example, the computer would go to a deep sleep on its own even though I set the power setting to never sleep. Another thing is that a few times when I press the power button (after shutdown), the computer would sound like it was starting but then it would go off after like two secs. Then I would have to press the power button again before it would boot up. Wondering if you ladies and gents would know what the likely cause is based on my description?

speedstep · Answer

760 is too old to pursue repair.  Especially when you can get a working unit for $100. https://www.lambroinc.com/desktops?lightbox=dataItem-jctxo0zm

bradthetechnut · Answer

Error code 3 indicates CPU failure. Why 3 only stays on with power button pressed, I don't know, but at least you got an indication.

The top CPU for the 760, Intel Core 2 Quad Q9650 3.0GHz, runs around $40 on eBay. You might still be safer to spend a little more and get a working or newer working unit.

Dell Optiplex Diagnostic Indicators

3

CPU

CPU configuration activity or failure; CPU Cache failure

Disconnect all external peripherals and configure PC down to PSU, Motherboard and CPU
If fault continues contact your technical support
If fault stops, plug disconnected parts back one at a time until fault re-occurs. Contact your technical support to take this further.

Optiplex Desktops

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