MP 1,1-5,1 5,1 dying when turned on three times then hanging endlessly with louder fan

[Sameyes]

Hi all. Please forgive me if this is the wrong place to post this but couldn’t see a better sub-forum.

I’ve had a Mac Pro 5,1 for nearing 10 years now, used to be my main machine for music production but has been a Plex server in my living room for the past 6 months (I’m aware there are more efficient ways to do it, it was just going unused and I can’t afford a separate server so I kept it on as that).

Tonight Plex was showing issues with transcoding, the storage hard drive was running very low on space but I didn’t see how much the boot drive (SSD) had left.

I thought resetting would help but since then it’s just been attempting to boot and cancelling after about 3 seconds. After three attempts it stays on, but with the fan running higher and nothing coming on the display.

I’m not sure if links work on here but here’s a video: https://www.dropbox.com/scl/fi/5qig...2-07.mov?rlkey=o0nf0ozchi9cqkt191yut8yuw&dl=0

Any help appreciated. I’m a novice and don’t have access to other similar machines (I have a M1 MacBook Pro and my partner has a Mac Mini but that’s it) and I generally don’t get involved in swapping out parts further than hard drives. Any idea what’s going on?

 

[h9826790]

Pull the power cord, then pull out the CPU tray and check the Northbrigde heatsink if still firmly attached.

 

[Sameyes]

Pull the power cord, then pull out the CPU tray and check the Northbrigde heatsink if still firmly attached.

Seems to be attached properly still, doesn’t move around at all. Inside was quite dusty overall, gave it a quick air blast and it’s looking a lot better but still no joy when turning it on.

 

[h9826790]

Seems to be attached properly still, doesn’t move around at all. Inside was quite dusty overall, gave it a quick air blast and it’s looking a lot better but still no joy when turning it on.

That plastic rivet can break anytime, no need to move it to trigger this failure.

If you can't hear the chime, then it's a very bad sign. Basically, if you removed the graphic card and all hard drives, and still can't hear the chime, then your cMP is dead (>90% logic board / CPU tray / PSU failure).

 

[Sameyes]

That plastic rivet can break anytime, no need to move it to trigger this failure.

If you can't hear the chime, then it's a very bad sign. Basically, if you removed the graphic card and all hard drives, and still can't hear the chime, then your cMP is dead (>90% logic board / CPU tray / PSU failure).

Graphics card and all hard drives removed, no chime. Although now after three or so attempts it stays on with a red light that hadn’t happened before. I’m assuming this is indicating a failure somewhere on the board?

 

[bax2023]

On the Dual CPU Mac Pro like yours, those are RAM memory diagnostic LEDs, so there are 8 small LEDs pointing to each memory slot. Check which exact LED is lit, and try Mac Pro without that memory stick.

 

[Sameyes]

On the Dual CPU Mac Pro like yours, those are RAM memory diagnostic LEDs, so there are 8 small LEDs pointing to each memory slot. Check which exact LED is lit, and try Mac Pro without that memory stick.

View attachment 2313557

Managed to get that light off by removing the RAM in the indicated slot but no change to the other symptoms.

Is there any explanation as to why, after failing to stay on two or three times, it turns on with the graphics card fan running much higher and it stays on indefinitely? Nothing shows on the display and there’s still no chime, but it stays turned on.

 

[bax2023]

It could be that Mac's EFI firmware did not even initialize due to some PCB issue on the backplane or EFI corruption.

There is also possibility, what @h9826790 suggested, that cooling of northbridge chip on the CPU tray failed due to broken one or both plastic rivets which should keep passive cooler in place with certain pressure on the chip. Those plastic rivets are 10+ years old and they are exposed to high temperature all the time. When I upgraded my CPUs, few months ago, I decided to replece the rivets with spings, and as soon as I touched on of them to remove it, it snaped off like thin glass.