2013 Mac Pro Trashcan - power light ok, no chime, black screen, unresponsive

Question

2013 Mac Pro Trashcan - power light ok, no chime, black screen, unresponsive

2013 Mac Pro Trashcan won't boot. 12 core. Fully spec'd Max Cpu, Ram, Gpu.

This black screen thing has happened a few times before over the last few years but has sorted itself out previously. This time no dice. I'm worried it is an ex-MacPro.

Symptoms;

Plugged in power cable. Fan starts. Power button light only turns on, no chime, black screen. No response when pressing the power button. Can only power off by holding the power button down.
Once powered off, upon pressing the power button again all the panel lights fade up for 15 seconds then they go out, and its back to the power button light on only, and still no chimes, black screen, unresponsive.
Have tried SMC Pram resets with a USB and Bluetooth Keyboards although due to it being so unresponsive its hard to know it's working.
Have tried taking ram out, leaving one stick in, using alternative oem 4gb stick, no response.
Previously have run hardware check and the machine is fine.

Seems like it's hanging upon that first plug-in in of the power, and after I force it to shut down it is caught in a loop where the lights fade up and then just loops back to a sleep kind of state.

Are there any different keystrokes on startup I can try to force the boot process to start?
Is it a sleep thing?
Is it a ram thing?
Flat board battery?

I do understand it could absolutely be a serious hardware issue with a component on the interconnect board or the cpu, gpu's etc but the machine is in perfect condition, clean inside and has been working perfectly. I am trying to find an alternative answer before I consider throwing it in the lake.

Considering how many posts there are of people with the exact same issue, I am hoping someone can help me find a few things to try. Any ideas welcome - thanks in advance!

Mac Pro, macOS 15.4

Posted on May 5, 2025 4:18 AM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

139,481 points

May 5, 2025 6:07 AM in response to Spillanegroup

<< Plugged in power cable. Fan starts. >>

That is NOT how it is supposed to work, and over a very large sample, that has suggested power supply issues.

you may hear a crackling/arcing as you insert the power cord, but it is not intended to power up on application of power. There is a small 'always on' power supply inside, so that is why it sometimes arcs a little at cord insertion.

The Caps lock light is a window into whether it has drawn the screen and is tracking the mouse and accepting input. These two features appear at the same time.

One of the simplest tests it to hold Alt/Option key ay startup. No drives are required to draw a gray screen, then add an icon for each potentially-bootable drive it can discover. All this code is in ROM. Wired keyboard directly on a USB on the chassis is preferred.

Anecdote suggests that a Mac with will not produce the second and subsequent chime when doing PRAM resets may have a failed PRAM battery.

On larger Mac Pro 42 lb tower models, failure of the PRAM backup battery can cause NO fans at power on request. In your model replacing that long life lithium coin cell with a fresh 3.00 volts or better replacement such as CR2032 is a 32-step tear-down.

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Answer 2

May 6, 2025 4:05 PM in response to Grant Bennet-Alder

Option key - no response (used an apple USB keyboard)

No chimes, same behaviour as described.

Interesting fact; I tried holding power button down when inserting the power cord. Result was the fan turned on full speed (louder than normal) and the power light didn't go on and had to shut down by holding the button in again. Again no response, just thought it was interesting.

FYI specs are;

2013 Mac Pro Trashcan model

12 cores

64Bg ram

Dual AMD FirePro D700 GPUs

256Gb SSD

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2013 Mac Pro Trashcan - power light ok, no chime, black screen, unresponsive

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