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zachek

macrumors member
Original poster
Jun 11, 2020
42
7
Los Angeles
I purchased this 12-Core Mac Pro 5,1 (see my sig) as-is a few weeks ago from a local reseller for a very low price. They had almost two dozen they were looking to move and in hindsight. I probably should have bought two for parts redundancy alone.

My plan was to spec it out (mostly for photo editing, with possibly some video editing and music creation as well--I’m a gaming tee-totaler.) I built my first computer around a Pentium II back in 1998, but in the last 10 years my hardware tinkering has consisted of only ram upgrades and data doubler SSD for optical drive swaps to multiple 2012 MBPs.

Immediately after purchase I plugged the 5,1 in to check it out, mostly to make sure a.) it worked and b.) the specs I was quoted were accurate. Foolishly, I did NOT run any real diagnostics at this time (wouldn't even know what to run tbh.) I just turned the machine off and continued my crash course on all of the possibilities in upgrading this machine.

Fast forward 3-1/2 weeks to two nights ago, and I’ve finally decided what I was upgrading (almost everything) and picked out, ordered and received all the new components. Even though I was still waiting on some HDDs for an internal RAID array, I had pretty much figured out my order of operations and was ready to begin.

But right off the bat I think I might have effed up. I opened the 5,1 and used this Metro Vacuum DataVac Pro to suck (with the straw type attachment with bristles) away some dust bunnies. In doing this I only touched the aluminum just in front of the old 5770 GPU and on the aluminum behind the PCIe fans (far left) of the middle compartment. I may have slightly brushed the 5770 once. I didn’t come near any other components or boards.

I then realized this was ill-advised and I hadn’t read at all in detail if this device was actually ESD proof or not or if this was even a good idea and stopped. Instead I switched it to blow and proceeded to blow a metric fton of dust out from everywhere in the machine (especially the CPU tray and the heat sinks, which I blew out while it was removed and set on my glass coffee table.) Before blowing inside the tower sans CPU tray, I tried to secure the PCIe fan by simply sticking a small rigid plastic pipe hose attachment from the Datavac through it so it would not spin up. I did NOT do the same with the CPU tray fans (because I wasn’t aware of them before I started blowing) but did not observe any movement from them throughout. At this time I did NOT blow out from within the optical drive bay or the PSU.

I pressed the power-on button and that button’s white LED came on. It chimed, the screen (a 42” TV monitor connected by HDMI with HDMI-DVI dongle) went white grey, and shortly thereafter I saw the Apple logo and a thin black progress bar. After it gets to about 20% the machine dies altogether.

Try this again and it happens again. And again.

At this point I tried resetting the NVRAM and the SMC. Then I tried replacing the BR2032 battery but all I had on hand was an old CR2032. Then I tried removing all RAM sticks except for one 4gb stick in slot 1. At some point within this phase, I stopped getting the white grey screen and apple logo and instead the machine would just die after a second or two, no chime.

Also during this phase, I can't tell you why exactly, but I may have held down the startup button for 5-6 seconds. From my reading this shouldn’t matter, but I was worried for a second I may have inadvertently initiated a firmware update attempt that then failed thereby bricking my system. But my CD tray never opened, so I’m not so sure. From my limited reading on that subject, it seems like I would need to have initiated this update from within macOS and my worry here is unwarranted.

Through this whole time, the cMP is plugged into a 1500va APC-UPS. During one of my early boot attempts I did watch the load bars on the UPS and saw the third bar appear (signifying 60% of the load according to the BR1500ms manual) just before the machine died. I then attempted to plug in to the wall directly but that changed nothing.

When I press the power-on, the top two diag LEDs (OVTMP CPUA & OVTMP CPUB) flash red. When the machine is off, only the 5V STANDBY amber LED can be seen when I press the diag LED button.

Watching the video of a startup attempt, the PCIe fan starts and run for about 1.5-2 seconds and then stop. I believe the CPU tray fans are the same. There is also a red LED on the CPU tray that flashes. It is labelled R1511.

I don't know how to attach video to this post, but you can see screen shots stills from both the videos in question.

I tried removing all RAM sticks, the HDD, the optical drive, the GPU and booting like that and nothing changed.

The strange thing was the next morning, I tried to power-on again and this time I heard a chime but it died again some time later (can't recall if i saw an apple logo or not.)

After reading as much as I could on this forum, Reddit and apple forums over the last 48 hours, I am at a loss. I’m guessing it is either the PSU, the backplane, the CPU tray, Northbridge spring rivets?

Should I try the new GPU or the new RAM? CMIIW but it seems like its not the RAM or the GPU because of the way removing both completely didn't seem to change anything with the diag LEDs.

Any and all help would be greatly appreciated.
 

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tsialex

Contributor
Jun 13, 2016
13,459
13,608
R1511 LED always flashes when you press power on, could be the PSU or the backplane since you don't have EFI DONE lit.

Even with the diagnostic steps from Apple Technician Guide, Mac Pros are very difficult to diagnose correctly without you having another one working to test the parts, try to get another one and test the PSU/backplane/CPU tray, one part at a time, with the working one. It's the fastest and cheapest way to get it working again, buying the parts separately will cost you more.

Btw, you need to install a BR2032 back after you get it working again, the chemistry of CR2032 is different and it won't resist the high temperatures near the GPU.
 

zachek

macrumors member
Original poster
Jun 11, 2020
42
7
Los Angeles
R1511 LED always flashes when you press power on

Thanks for this. Try as I might, I somehow couldn't confirm that.

could be the PSU or the backplane since you don't have EFI DONE lit.

good to know thanks.

Even with the diagnostic steps from Apple Technician Guide, Mac Pros are very difficult to diagnose correctly without you having another one working to test the parts, try to get another one and test the PSU/backplane/CPU tray, one part at a time, with the working one. It's the fastest and cheapest way to get it working again, buying the parts separately will cost you more.
I was starting to realize that after I priced out what all these replacements would cost.

I should only be looking for dual cpu tray 5,1’s correct? ie Im assuming there are functional differences between backplanes and CPU trays between flashed 4,1’s and actual 5,1s? I know the PSUs are basically the same but not sure about the rest.

Btw, you need to install a BR2032 back after you get it working again, the chemistry of CR2032 is different and it won't resist the high temperatures near the GPU.
Thank you for confirming that also, and thank you for reading that very lengthy post in detail! I have some on order now. I included that info not knowing for sure if that could be a simple fix. Wishful thinking that.

Many thanks again for answering so quickly, and for all of your contributions on this board!
 

tsialex

Contributor
Jun 13, 2016
13,459
13,608
Thanks for this. Try as I might, I somehow couldn't confirm that.



good to know thanks.


I was starting to realize that after I priced out what all these replacements would cost.

I should only be looking for dual cpu tray 5,1’s correct? ie Im assuming there are functional differences between backplanes and CPU trays between flashed 4,1’s and actual 5,1s? I know the PSUs are basically the same but not sure about the rest.


Thank you for confirming that also, and thank you for reading that very lengthy post in detail! I have some on order now. I included that info not knowing for sure if that could be a simple fix. Wishful thinking that.

Many thanks again for answering so quickly, and for all of your contributions on this board!
You can test with any Mac Pro 4,1 or 5,1, single or dual. The PSU is the same for all 3 model years and you can use a 2009 backplane to test 2010/2012 ones, but the fans will go on full RPM full time since the early-2009 SMC is 1.39f5 and mid-2010/mid-2012 is 1.39f11. SMC can't be updated, btw.

Buy the cheapest working Mac Pro you can find, diagnose yours, then buy just the defective parts. If you find a mid-2010 or mid-2012, all parts are interchangeable. With early-2009, you can't use the backplane/CPU tray besides for diagnostics - no one can stay by the side of a Mac Pro running all fans at full RPM, full time.
 

zachek

macrumors member
Original poster
Jun 11, 2020
42
7
Los Angeles
You can test with any Mac Pro 4,1 or 5,1, single or dual. The PSU is the same for all 3 model years and you can use a 2009 backplane to test 2010/2012 ones, but the fans will go on full RPM full time since the early-2009 SMC is 1.39f5 and mid-2010/mid-2012 is 1.39f11. SMC can't be updated, btw.

This is great to know, since I was going to ask next what is a dead giveaway to distinguish a real 5,1 from a flashed 5,1. I found a local seller with a dual processor tray 5,1 and I verified in system report the 1,39f11 SMC so I'm going to just get that.

Considering how labor intensive it seems replacing the backplane would be, I think I will test the old CPU tray in the newer 5,1 first, then the PSU. Is there any software I can use to test the integrity of either?

If it isn't the PSU or the CPU tray that is faulty I may just end up doing all of the upgrades on the new 5,1 instead of replacing the backplane. Not sure if I'm ready for a backplane swap just yet, as I'm still a bit gun-shy thinking I may have fried the last one.

Functionally, I wouldn't be sacrificing any performance by upgrading the 2010 over the 2012, correct? The 2010 can still take the 3.46 x5690s yes?
 

tsialex

Contributor
Jun 13, 2016
13,459
13,608
This is great to know, since I was going to ask next what is a dead giveaway to distinguish a real 5,1 from a flashed 5,1. I found a local seller with a dual processor tray 5,1 and I verified in system report the 1,39f11 SMC so I'm going to just get that.

Considering how labor intensive it seems replacing the backplane would be, I think I will test the old CPU tray in the newer 5,1 first, then the PSU. Is there any software I can use to test the integrity of either?
AHT and ASD (if you can find it, since its an internal Apple tool and you'll only find torrents)

If it isn't the PSU or the CPU tray that is faulty I may just end up doing all of the upgrades on the new 5,1 instead of replacing the backplane. Not sure if I'm ready for a backplane swap just yet, as I'm still a bit gun-shy thinking I may have fried the last one.

Functionally, I wouldn't be sacrificing any performance by upgrading the 2010 over the 2012, correct? The 2010 can still take the 3.46 x5690s yes?
Mac Pros are identical for mid-2010 and mid-2012 and all parts are interchangeable, both support the exactly same processors.

MP4,1 and MP5,1 are the exactly same platform. After you cross flash the MP5,1 firmware to a MP4,1, you can use all the CPUs that are supported with MP5,1 firmwares. The only real difference, after you take of GPUs, Wi-Fi and processor options at the time, are the SMC firmware version used on backplanes and CPU trays.

For single CPU Mac Pros, Apple only changed the SMC firmware from early-2009 to mid-2010/mid-2012. Not one other internal part, besides the GPU and processor, changed in the four years that the platform were produced.

For dual CPU Mac Pros, besides the SMC firmware, Apple initially used de-lidded processors with early-2009, then got back to normal lidded ones with mid-2010/mid-2012 models. The processor socket and heatsink base changed, the heatsinks of a early-2009 dual CPU tray can only be used with another early-2009 dual CPU tray, but everything else on the CPU tray is exactly the same from early 2009 to mid-2010/mid-2012.

Since the early-2009 models, the only thing that changed with Mac Pros are the GPUs and the processors sold by Apple. Early-2009 Mac Pros had as GPU options GT-120 and HD 4870, while mid-2010 and mid-2012 had HD 5770/5870. With CPUs, Early-2009 only MP4,1 firmware only supported Nehalem Xeons, while mid-2010 and mid-2012 firmware supported Nehalem and Westmere Xeons. Mid-2012 had six core Westmere processors as an CTO option. All other components, except what I wrote above, are the same from early-2009 to mid-2012.

One last thing before I forget, early-2009 Mac Pros had the AirPort Extreme as a factory option while with mid-2010/mid-2012 Apple made the Wi-Fi as a standard item. Some early-2009 had BCM94321MC as the AirPort Extreme, a card that only was supported up to Sierra. Mid-2010/mid-2012 AirPort Extreme is BCM94322MC and this one was supported up to Mojave, Apple removed it from Catalina.
 
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