So I recently picked up a Mac Pro 5,1 for free. It has 8gb of ram, dual 4c/8t cpus and a hd 5770. Originally I couldn’t even get it to stay on for more than 5 seconds it would click, fans spin, and then click off. Now after reseating the cpus and cpu tray it turns on and the fans spin. I have never gotten the startup chime or display. The standby, efi done, and gpu good lights are lit when pressing the diag button. It exhibits the same behavior with or without the gpu. What should I try to diag this issue? Thanks!
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MP 1,1-5,1 Mac Pro 5,1 No boot or chime
- Thread starter ac6000tr
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It does not get far enough to turn on usb power. Just sits there with the fans running. Power light steady not blinking. No lights on cpu tray other than when it’s plugged in or turned off for less than 1 sec.
Can you see any red lights on the cpu tray near the RAM?
Red light indicates failed DIMM
You could try removing all but one DIMM, the gpu and the hard drives and try to start up, of course it won't boot with no HD, but at least you might get a chime.
another thing to check is failed Northbridge heatsink rivets. its an aluminium heatsink near the cpu.
Red light indicates failed DIMM
You could try removing all but one DIMM, the gpu and the hard drives and try to start up, of course it won't boot with no HD, but at least you might get a chime.
another thing to check is failed Northbridge heatsink rivets. its an aluminium heatsink near the cpu.
No red lights except right at startup for less than a second. I currently have one dimm and tried one then two cpus and still no chime just fans. Would the loose rivets cause a no start? I was under the assumption that it would cause stability issues and crashes after boot.
Check the button battery voltage. If your used Mac Pro was in storage for a long time, the battery could be drained.
My first guess is the power supply. But there are things you can check:
When you remove the 5770, did you also unplug the aux power cables? If the 5770 were blown and overdrawing on the aux power, it would cause an immediate shutdown.
Try reseating the power plug to the logic board - it's hidden behind the access panel, behind the optical drives.
It might help to spray the contacts with electronic contacts cleaner: the CPU tray contacts, and the logic board power connector contacts.
Also, if you pull the CPUs again, check the socket arrays for any bent or broken pins. Anything that doesn't fit into the array pattern.
My first guess is the power supply. But there are things you can check:
When you remove the 5770, did you also unplug the aux power cables? If the 5770 were blown and overdrawing on the aux power, it would cause an immediate shutdown.
Try reseating the power plug to the logic board - it's hidden behind the access panel, behind the optical drives.
It might help to spray the contacts with electronic contacts cleaner: the CPU tray contacts, and the logic board power connector contacts.
Also, if you pull the CPUs again, check the socket arrays for any bent or broken pins. Anything that doesn't fit into the array pattern.
I replaced the battery and it did not change the behavior. I tried reseating the connector and that did not change it either. When I had the CPUs out before I did check for bad pins and I didn’t see any. I also did unplug the GPU and fully remove it from the case. Are there any dead giveaways that it could be the psu? Since after reseating I can get the fans to spin with no blinking red lights or anything weird visually inside the case and it doesn’t shut off anymore.
Fans are not full blast. I actually only have one of the coolers on cpu A as cpu b does not get hot enough fast enough for me to care. But this is strange behavior as I would think with the thermal sensor and the cooler removed the fans should be full blast.
How many blinks? There should be blinks, then a pause, then the blinks repeat, pause, etc.
Don't stress over the lack of a boot chime. If the last user was using digital-out (or set system volume to zero) then there would be no chime. Once you get far enough for a PRAM reset, that should restore the chime. Until then, the lack of a chime isn't conclusive.
I suspect a weak PSU, or the front panel board with power button has a problem. But it's encouraging that you have steady power now. Does USB power appear? Any USB device that has a power indicator can be used to check if USB is powered on. If the system reaches USB power, then you can do a PRAM reset with a known-good keyboard.
If the front panel board has a problem, you can check by disconnecting the front panel board. Then short the proper contacts to begin a power-up. See the service manual for a picture, showing the proper contacts to momentarily short.
I suspect a weak PSU, or the front panel board with power button has a problem. But it's encouraging that you have steady power now. Does USB power appear? Any USB device that has a power indicator can be used to check if USB is powered on. If the system reaches USB power, then you can do a PRAM reset with a known-good keyboard.
If the front panel board has a problem, you can check by disconnecting the front panel board. Then short the proper contacts to begin a power-up. See the service manual for a picture, showing the proper contacts to momentarily short.
Unfortunately I still don’t have any usb power. I’ll see if I can find a cheap known good PSU
what about pressing the Clock reset button near the RTC battery.
You can remove the battery completely and try starting without it.
I have done both of those things with the same results unfortunately. I will try again when I am home from work to double check. I have been thinking of trying to was the cpu board with some isopropyl alcohol to remove all the dust. It does have a lot of build up.
I wish that was the case but I feel because of the no usb power there is something else going on.
That sounds like a single blink, which means no RAM detected, or RAM failed the memory quick test.
I didn't catch this earlier. The RAM LEDs are not the diagnostic ones on the backplane (logic board), near the power button. Rather, they are a bank of red LEDs on the processor board, near the RAM slots. If a RAM slot is empty, the corresponding LED should be illuminated steadily. ie - on a dual-CPU board like yours, if one stick is installed, you should get at least 7 red LEDs glowing near the RAM slots, one for each empty slot. You'll get 8 red LEDs if the stick you're testing with is bad, or poorly seated.
The RAM LEDs on a dual-CPU are visible in your pic above, with a CPU removed - between missing CPU and rear RAM slots. Look forwards of the rear RAM slots - there's a black power connector (thermal sensor plug for CPU A) coming up behind a black screw. The 8 LEDs are just forwards (left) of the black screw. They look like little yellow boxes when they're unpowered.
Edit: To clarify, it still sounds like a weak PS. But it's possible from earlier posts, you were checking the wrong LED bank for RAM tests. If the one RAM stick used for testing were bad, it would explain everything - before laying out cash for a PS. Seems worth asking about, just to be sure.
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Hmmm well none of the ram lights ever turn on, even with zero sticks installed. To be clear here when I have one ram stick installed the light on the front is solid and not blinking. When I remove the sticks is when it blinks. Sometimes, not always even with no ram the light will stay solid. This is probably 10% of the time or less. Also sometimes the system still switches off immediately. I tried to rule out a bad ram stick but once I was sure it was one bad stick it started turned on with that one. When I say turned on I mean it turned on the fans and front panel light.
The initial report of a blinking light on the front. I didn't realize right away it probably counted as a single-blink pattern.
A weak power source can cause any power indicator to cycle - think of a bad CFL light bulb flashing as it tries to start up, but there just isn't enough juice on tap. Also, a PS is somewhat more likely to have issues vs other modules because PS components are stressed by high currents and temps on a regular basis.
However, you raise a good point. The diagnostic LEDs are steady - they'd probably cycle too if the PS were barely putting out juice at all. And I don't like the RAM LEDs not coming on. So I'm switching theories away from the PS.
Unfortunately, I'm not sure what advice to give now. At this point, you'd want to swap CPU tray with a working Mac Pro. Major component swaps are the simplest way to narrow down the problem. If you don't have a spare Mac Pro available, then I've run out of inexpensive diagnostic steps. Sorry.
A weak power source can cause any power indicator to cycle - think of a bad CFL light bulb flashing as it tries to start up, but there just isn't enough juice on tap. Also, a PS is somewhat more likely to have issues vs other modules because PS components are stressed by high currents and temps on a regular basis.
However, you raise a good point. The diagnostic LEDs are steady - they'd probably cycle too if the PS were barely putting out juice at all. And I don't like the RAM LEDs not coming on. So I'm switching theories away from the PS.
Unfortunately, I'm not sure what advice to give now. At this point, you'd want to swap CPU tray with a working Mac Pro. Major component swaps are the simplest way to narrow down the problem. If you don't have a spare Mac Pro available, then I've run out of inexpensive diagnostic steps. Sorry.