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Mac Pro Early 2009 (4,1) Driving me insane

T

^Tripper^

macrumors member
Original poster
Oct 31, 2010
64
45
Disneyland with the Death Penalty
I've got a 4,1 that is seriously driving me insane. Some background;

cMP, Early 2009 (4,1), Quad core 2.66, 32GB RAM (4X 8GB sticks)

I was using it a few months back when it suddenly died. Middle of work and it shut down. Couldn't get it to power back up. Checked out the forums, did a little research and figured it was a wonky PSU unit. Couldn't spare the time to get it fixed at that time, so I left it and just worked on my MacBook Pro instead.

A couple of months later, figured it's time to get it back up and running. Plugged it in and it worked! For a while before it shuts down again. Did some trouble shooting, opened it up and checked out the internals. It would boot up but then shut down after a few minutes. Noticed that the fan in front of the PSU unit was not spinning when powered up. Made sense, the cMP was going into thermal shut down I thought. Sourced high and low for a replacement fan which I finally found and replaced it. No dice. The cMP would boot, run for awhile before shutting off again. Its the PSU I thought. Ok, so be it, lets just get it replaced.

Purchased a new PSU and gleefully I replaced it thinking my issues are over. BUT NO!!! Still having the same issue!!!! It'll boot up, run for awhile before shutting down again!

Could be the new PSU I got had the same issue (it is suppose to be brand new thou). I can reach out to the seller, but I'd like to eliminate all other possibilities first.

I've tried the usual troubleshooting steps, reset everything that could be reset (NVRAM, SMC, RTC) removed all peripherals (USB except for keyboard and mouse), no PCI-E cards other then the stock video card (NVIDIA GeForce GT 120), removed RAM, cleaned out every last dust bunny and its mother. I even followed the steps in the 'Apple Technician Guide' and brought it down to a minimal testing configuration. I even took off the heatsink, cleaned out the old thermal paste and reapplied new paste. Even did that for the north bridge chip heat sink....

Even tried to restore the firmware by creating a 'Firmware restore CD' as per apple instructions but am unable to do it as the cMP does not stay on long enough for me to effect that restore.

I'm seriously out of ideas. I'm sure its something stupid and simple I'm missing.

I'd really like to get to the bottom of this.

Any and all inputs appreciated.

Thanks guys!!
 
When you open the case and watch the diagnose LEDs, can you see any of those light up when freezing? Are you able to run Apple Hardware Test (press and hold D at startup)?
 
Check the temperatures via iStat or HWMonitor etc may give you a better picture of what's happening (if that's really due to overheat). Self shutdown now necessary PSU related.
 
Was able to get into Apple hardware test but the mac would suddenly shut down in the middle of the test.

There is no "freeze", the mac suddenly and completely shuts down, so led diagnostics not helping much. When I ran it in the 'minimum configuration' setup, everything lit up the way it should "5V STBY, GPUOK" etc.

Just tried booting it up again. Stayed on for about 5 seconds. Sigh.
 
RAM trouble may freeze the machine or self restart, but a bit unusual to cause self shutdown, isn't it? Anyway, it's nothing wrong to have a try (especially if it's not ECC RAM), just install one stick only in one of the slot. If same fault, another stick in another slot. If same fault again, then the chance of RAM's failure is low.

Also, may be its time to open up the heatsink, re-plaste it, make sure it's not the CPU / north bridge overheat.
 
h9826790 said:
RAM trouble may freeze the machine or self restart, but a bit unusual to cause self shutdown, isn't it? Anyway, it's nothing wrong to have a try (especially if it's not ECC RAM), just install one stick only in one of the slot. If same fault, another stick in another slot. If same fault again, then the chance of RAM's failure is low.

Also, may be its time to open up the heatsink, re-plaste it, make sure it's not the CPU / north bridge overheat.
Click to expand...


Will try the RAM again. I did try that before and no change. Takes a bit of time to try this as after the Mac shuts down, it refuses to power back up for some time. I have to unplug it from the wall outlet and wait. Sometimes I have to wait for about two smokes, sometimes longer. But will try all the sticks again.

I have reapplied the paste on the processor and the northbridge chip. No difference.
 
h9826790 said:
RAM trouble may freeze the machine or self restart, but a bit unusual to cause self shutdown, isn't it? Anyway, it's nothing wrong to have a try (especially if it's not ECC RAM), just install one stick only in one of the slot. If same fault, another stick in another slot. If same fault again, then the chance of RAM's failure is low.

Also, may be its time to open up the heatsink, re-plaste it, make sure it's not the CPU / north bridge overheat.
Click to expand...

A coworker of mine handed me a 17" MBP that he was about ready to get rid of because it would randomly shut down. It would pass AHT it was running cool with no obvious issues I put two new sticks of RAM and the problem went away RAM is my pretty much my first thought when random strange stuff is happening problem come around.
 
Yeah, this really sounds PSU related still :/
^Tripper^ said:
Will try the RAM again. I did try that before and no change. Takes a bit of time to try this as after the Mac shuts down, it refuses to power back up for some time. I have to unplug it from the wall outlet and wait. Sometimes I have to wait for about two smokes, sometimes longer. But will try all the sticks again.

I have reapplied the paste on the processor and the northbridge chip. No difference.
Click to expand...

The thing about replacing thermal paste on the northbridge is that the retention pins are quite fragile and can break when even carefully handling these. You're sure the northbridge heatsink makes properly contact?
 
bokkow said:
Yeah, this really sounds PSU related still :/


The thing about replacing thermal paste on the northbridge is that the retention pins are quite fragile and can break when even carefully handling these. You're sure the northbridge heatsink makes properly contact?
Click to expand...

Yeah, read about how those pins can fail. Checked em before taking the heat sink off and they looked fine. Took the heat sink off, cleaned up the old paste and reapplied new paste. Put the heatsink back and made sure it was seated properly. Everything looks ok, seated fine. Perhaps I should just try replacing the retention pins? I've seen folks use screws instead. I'll prolly try that next if nothing else works.
 
Just tried booting up using a single stick of RAM as h9826790 suggested. Tried all of em one by one. No difference.

I can only think it's still a either a wonky PSU, some thermal issue or some weird boot up ROM EFI thing.
 
If the CPU heatsink is working, is there any other component will overheat in just few seconds after the machine boot?

Did you try other power socket?
 
h9826790 said:
If the CPU heatsink is working, is there any other component will overheat in just few seconds after the machine boot?

Did you try other power socket?
Click to expand...

I can only think of the northbridge chip. It is also cooled by the fan in the CPU heatsink, which is confirmed working.

Power socket? Why not? Just tried it, no change. Just tried another power cable as well, no change either.
 
DearthnVader said:
Sounds like your Logic Board has failed. You could go on and on chasing your tail, but noting but a new Logic Board is going to fix the trouble.
Click to expand...

If it is the logic board, I don't mind replacing it if I can find one at a reasonable price. Just wanna make sure that's the problem before I purchase another part. Don't suppose there is a way to test that without replacing it?
 
You could try exchanging your CPU tray with one of a friends', just to make absolutely sure the problem is not with this tray, CPU, cooling of CPU/NB or memory. That is the fastest way to rule out a lot of possible causes
 
bokkow said:
You could try exchanging your CPU tray with one of a friends', just to make absolutely sure the problem is not with this tray, CPU, cooling of CPU/NB or memory. That is the fastest way to rule out a lot of possible causes
Click to expand...

Would've tried that if any of my friends used macs too, am surrounded by windoze users. I'm the 'Mac' guy. Heh.
Oh well. I'll figure something out. For now, I'm gonna try replacing the nylon pins on the northbridge and reapply the paste again and see if that works. Gonna head down to the local electronics parts mall and pick some stuff up.

As annoying as this issue is, it's been awhile since I've been stumped by a Mac issue that I couldn't solve and I'm kinda enjoying it. I'm such a sucker for pain I guess. (Except the expensive kind!!!)
 
h9826790 said:
RAM trouble may freeze the machine or self restart, but a bit unusual to cause self shutdown, isn't it? Anyway, it's nothing wrong to have a try (especially if it's not ECC RAM), just install one stick only in one of the slot. If same fault, another stick in another slot. If same fault again, then the chance of RAM's failure is low.

Also, may be its time to open up the heatsink, re-plaste it, make sure it's not the CPU / north bridge overheat.
Click to expand...
^Tripper^ said:
Would've tried that if any of my friends used macs too, am surrounded by windoze users. I'm the 'Mac' guy. Heh.
Oh well. I'll figure something out. For now, I'm gonna try replacing the nylon pins on the northbridge and reapply the paste again and see if that works. Gonna head down to the local electronics parts mall and pick some stuff up.

As annoying as this issue is, it's been awhile since I've been stumped by a Mac issue that I couldn't solve and I'm kinda enjoying it. I'm such a sucker for pain I guess. (Except the expensive kind!!!)
Click to expand...

Could be the CPU booster fan instead of the heat sink. If the problem is the logic board though, you may be better off just buying a new machine...logic board alone could run you hundreds, plus the time and stress to switch it's out, and it may not work anyway if the logic board wasn't the problem. A new machine would not cost much more than a logic board.
 
^Tripper^ said:
Nope. Mac shuts down before I can boot up.
Click to expand...
well, you would do those things before initiating the boot.. mainly just to rule out a software problem but occasionally it could help pinpoint a hardware problem.
that said, it was a longshot suggestion anyway ;)
 
flehman said:
Could be the CPU booster fan instead of the heat sink. If the problem is the logic board though, you may be better off just buying a new machine...logic board alone could run you hundreds, plus the time and stress to switch it's out, and it may not work anyway if the logic board wasn't the problem. A new machine would not cost much more than a logic board.
Click to expand...

Yeah, the prices of the logic board are high. That said, considering where I'm located (i'm in asia) the cost of shipping still makes getting a logic board a viable option IF i can find one that isn't insanely expensive. That is if i'm sure its a logic board issue. So only way now I feel is to slowly try all other options to narrow down the fault. Whack-a-mole time.

As it is, the symptoms still suggest to me a PSU issue.
 
flat five said:
well, you would do those things before initiating the boot.. mainly just to rule out a software problem but occasionally it could help pinpoint a hardware problem.
that said, it was a longshot suggestion anyway ;)
Click to expand...

Appreciate all suggestions, long shots or otherwise!!

For some reason, I'm determined to get to the bottom of this. Most to most, the mac is toast and I'm out one lovely machine. But I gotta be able to try everything to satisfy my curiosity. Perhaps I'll learn something new which can only help the community.
 
^Tripper^ said:
Appreciate all suggestions, long shots or otherwise!!

For some reason, I'm determined to get to the bottom of this. Most to most, the mac is toast and I'm out one lovely machine. But I gotta be able to try everything to satisfy my curiosity. Perhaps I'll learn something new which can only help the community.
Click to expand...

We had similar issues with a 2007 (2,1) 8 core while it was under warranty. Apple ended up replacing the logic board which solved the issue. It was as if a trace was flexing as the board temp changed and caused either a fault or an open circuit.

Good luck.
 
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