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Help! 2009 won’t reboot!

BrotherJerome

BrotherJerome

macrumors member
Original poster
Dec 2, 2015
33
5
Raleigh, NC
So I was just browsing and the screen froze. Unresponsive. I did a hard reboot (unplugged the power cable), and now it won’t reboot. I get power, fans, and I can hear the drives spin up at first. But no startup chime and no video.

So I unplugged all peripherals, took out all drives except the boot drive, reset the SMC, tried different outputs from the GPU (Mac flashed Radeon 7950). Nothing.

Next, I took out the ram chips and reinstalled them one at a time, i reinstalled the *original* ram chips one at a time, reinstalled the original GPU, installed a new 2032 button battery and hit the battery reset button. Still just fans and drive spin-up, but no chime and no video.

Any other ideas?? It’s a 2009 (flashed to 5.1) with 16 GB RAM, and a 500 GB SSD main drive.
 
Last edited:
Synchro3 said:
Do you see any red lights?

Did you check the northbridge heatsink rivets? https://forums.macrumors.com/thread...ng-broken-northbridge-heatsink-rivet.2046462/

However, recently I had to replace the motherboard, no red lights, fans running, but no chime. https://forums.macrumors.com/threads/mac-pro-5-1-no-boot-up-black-screen.2124447/#post-26201323

By the way: Never unplug the power cable for hard reboot, always hold the On/Off-button for 10 seconds.
Click to expand...

I’m hesitant to mess with the CPU, so I haven’t checked the Northbridge rivets yet. No red lights though. And yeah, I won’t make the mistake of hard rebooting with the power cable again.
 
No red lights, fans running, no chime. I guess the motherboard failed. However, you should first the check the northbridge heatsink rivets, because this is the best case scenario.

Here you go: Mac Pro Technician Guide
 
The problem is, all three following failure can cause the exact same behaviour.

A) logic board fail
B) CPU tray fail
C) PSU fail

It’s really hard to tell which is the root cause without swapping test.
 
He gets power and are fans running, so it should not be a PSU fail.
 
Synchro3 said:
He gets power and are fans running, so it should not be a PSU fail.
Click to expand...

No necessary. Your assumption only applicable to a completely dead PSU. There are many cases a cMP show that symptom because PSU partly failed.

If you assume a completely dead logic board, the cMP also won’t power up at all. However, partly fail can cause that symptom (which fit your case).
 
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