Resolved There is a problem with cold startup of Mac Pro 2009

[ZNDK]

I have been using 48GB of memory and have added two 8GB memory cards to make 64GB. Since then I have had difficulty cold starting my Mac. When I press the power button it does not make the startup sound forever and the apple symbol does not appear. I left it in this state for an entire day and it never started up.

I have reduced the memory and the condition is no longer the same. The weird part is when I boot up without a single piece of memory set. Usually the white LED on the front flashes if there is no memory. But during this symptom the LED is always on.

I can get it to boot up by trying several times. It's just good or bad luck.
I have tried changing video cards (RX580, GT120, Vega 56), power supply units and CPU (X5675-E5520) and OS downgrade and PRAM reset and SMC reset but no change. I recently got my backplate and it seems to be incompatible with the CPU Tray as the firmware versions seem to be different. All the fans are running at full speed. This situation but no change as far as booting is concerned. The remaining verification is CPU Tray, but I can't get it because 2009 is not sold around me.

Rebooting is not a problem at all.
Is there any way to solve this startup problem?

 

[tsialex]

I recently got my backplate and it seems to be incompatible with the CPU Tray as the firmware versions seem to be different. All the fans are running at full speed.

Backplate is the metal plate that reinforce the back of a modern GPU to avoid it from bending.

You are trying to say backplane? So, you bought a mid-2010/mid-2012 backplane for an early-2009 Mac Pro?

That is a SMC mismatch situation and needs to be corrected, replacing the backplane for another one of the correct year model or buying a compatible CPU tray.

This situation but no change as far as booting is concerned. The remaining verification is CPU Tray, but I can't get it because 2009 is not sold around me.

Now the most reasonable thing that you can do is to buy a mid-2010/mid-2012 CPU tray and make a matched mid-2010/mid-2012 backplane/CPU tray combo.

 

[ZNDK]

You are trying to say backplane? So, you bought a mid-2010/mid-2012 backplane for an early-2009 Mac Pro?

I bought one that was sold for 2009. Eventually I switched to it and there was no change in the cold boot problem, so I knew it wasn't the cause. I believe the remaining problem potential is in CPU Tray.

 

[tsialex]

I bought one that was sold for 2009.

I recently got my backplate and it seems to be incompatible with the CPU Tray as the firmware versions seem to be different. All the fans are running at full speed.

You need to decide which statement is the correct one. Both can't be right.

SMC firmware needs to match between the backplane and CPU tray. Both need to be 1.39f5 (early-2009) or 1.39f11 (mid-2010/mid-2012).

 

[ZNDK]

Then I was lucky enough to get my hands on a 2009 CPU tray(as-is item). Then the tightness of the CPU heatsink is severe, but basically normal startup is now possible. The maximum memory capacity has also been increased. In the past, when the memory capacity exceeded 56GB, the memory speed dropped to 700MHz, or the CPU tray didn't recognize the memor(card) that exceeded 56GB.

Did the original CPU tray already have some anomaly and memory expansion triggered it to break? I don't know the definite cause.