MP 1,1-5,1 Perplexing repair issues (cMP4,1 to 5,1)

[GhostImage]

With the help of this forum, I took a MP 4,1 flashed it to a 5,1 and installed NVME to help speed it up. Then suddenly and without warning, it would no longer start up. I narrowed the issue down to the CPU tray with the help of a certified Apple tech. (The machine would boot with the chime via a different CPU tray.) Believing it to be a failed CPU (it is a dual CPU system), I bought and replaced the CPUs. After carefully replacing the CPUs, it still will not boot or even give the start up chime. I am wondering if anyone has any insight or recommendation as to how to fix the tray issue. I know there are used or refurbished trays available. I probably should have bought one. I opted for the less expensive choice of the CPUs instead. I live in the LA area but the tech and repair ppl will not attempt to solve the problem. They say he cost is more than the cMP is worth. Any suggestions would be greatly appreciated.

 

[Snow Tiger]

Your Certified Apple Tech failed to certifiably inform you about certifiably failed Northbridge Controller chips and their Heatsinks .

Examine both push pin fasteners to see if they are still retaining that Heatsink . You also need to re-thermal paste the Northbridge chip with a fresh coating of Arctic MX4 . Remove the dried factory paste first with alcohol , cotton swabs and use a black stick to gently scrape away stubborn dried paste .

 

[GhostImage]

Your Certified Apple Tech failed to certifiably inform you about certifiably failed Northbridge Controller chips and their Heatsinks .

Examine both push pin fasteners to see if they are still retaining that Heatsink . You also need to re-thermal paste the Northbridge chip with a fresh coating of Arctic MX4 . Remove the dried factory paste first with alcohol , cotton swabs and use a black stick to gently scrape away stubborn dried paste .

Thank you for this insight. I will look to see if this is the solves the problem. The two techs I consulted did not let me know this was an issue.

Can you recommend a site or a document that can guide me through this process?

 

[MIKX]

Did you install LIDDED or UN-LIDDED CPUs ?

In case you don't know, the LID is called the IHS; it's the cover on top of the CPU.

Any red lights showig i the CPU Tray ?

 

[Snow Tiger]

Thank you for this insight. I will look to see if this is the solves the problem. The two techs I consulted did not let me know this was an issue.

That's because it's not in the official service source .

Can you recommend a site or a document that can guide me through this process?

There are a lot of instructionals here at MR . Just look for Mac Pro CPU Tray Northbridge .
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Did you install LIDDED or UN-LIDDED CPUs ?

In case you don't know, the LID is called the IHS; it's the cover on top of the CPU.

Any red lights showig i the CPU Tray ?

His issue occurred before he upgraded the CPUs . And another CPU Tray worked in his System . So , his original Tray failed , most likely the NB Chip and HS .

 

[GhostImage]

Did you install LIDDED or UN-LIDDED CPUs ?

In case you don't know, the LID is called the IHS; it's the cover on top of the CPU.

Any red lights showig i the CPU Tray ?

I installed CPUs without LID or Integated Heat Sinks.
I only get a very brief red light at initial pushing of the power button. It flashes on and off quite quickly.

 

[tsialex]

I installed CPUs without LID or Integated Heat Sinks.
I only get a very brief red light at initial pushing of the power button. It flashes on and off quite quickly.

This is the behaviour for all trays at power on. You say that the problem is the tray, but did you tested if you can boot with another tray? The technician showed it booting with another tray?

 

[Snow Tiger]

I installed CPUs without LID or Integated Heat Sinks.
I only get a very brief red light at initial pushing of the power button. It flashes on and off quite quickly.

DO you have another Mac Pro 4,1 upgraded 5,1 to test your DP Tray with ? In a pinch , you could install it in a factory Mac Pro 5,1 , but the system fans will spin up to max .

Do not use a straight , factory Mac Pro 4,1 if you installed six core CPUs or the Quad Core X5677 CPU .

 

[GhostImage]

This is the behaviour for all trays at power on. You say that the problem is the tray, but did you tested if you can boot with another tray? The technician showed it booting with another tray?

The tech was able to get the cMP to start up with chimes using another tray. It indicated the 5,1 flash despite using a 4,1 tray too.

 

[tsialex]

The tech was able to get the cMP to start up with chimes using another tray. It indicated the 5,1 flash despite using a 4,1 tray too.

If you saw it booting, seems your tray is dead. A tray with damaged northbridge heatsink pins still boots, it only stops booting when the northbridge really dies.

The cheapest way to get you going again is to buy a single CPU tray for a 2009 Mac Pro, you can get one on eBay for around $50. A dual CPU tray is around $400 to $500 on eBay, sometimes you can get a full dual CPU 2009 Mac Pro for less than that from Craigslist.

Pay attention that single or dual CPU trays for 2010/2012 won't work for you, SMC mismatch version and it can't be corrected. You have to buy a 2009 tray for a 2009 Mac Pro or all your Mac Pro fans will run at full RPM/full time.

 

[GhostImage]

DO you have another Mac Pro 4,1 upgraded 5,1 to test your DP Tray with ? In a pinch , you could install it in a factory Mac Pro 5,1 , but the system fans will spin up to max .

Do not use a straight , factory Mac Pro 4,1 if you installed six core CPUs or the Quad Core X5677 CPU .

It seems as if I will need a replacement tray since I cannot visualize the Northbridge problem and solution. Pardon my lack of expertise. The Northbridge "rivet" issue seems familiar to those in MR discussion. It is new to me. Now I am concerned that I will/might get the wrong tray. I feel out of my depth.

 

[tsialex]

It seems as if I will need a replacement tray since I cannot visualize the Northbridge problem and solution. Pardon my lack of expertise. The Northbridge "rivet" issue seems familiar to those in MR discussion. It is new to me. Now I am concerned that I will/might get the wrong tray. I feel out of my depth.

Search for 2009 Mac Pro CPU tray:

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Search for Mac Pro 4,1 CPU tray

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With some searching you can get a single CPU tray for around $50 + shipping. I got two recently.