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ppinter1

macrumors newbie
Original poster
Sep 4, 2008
14
6
Long story short: my mid-2010 cMP5,1 started exhibiting symptoms of Flash ROM corruption such as failure to find bootable USB, et al.

Using 4-bong NVRAM resets, ROMTool/UEFITool consistently shows 24KB of free space. But, I'm afraid it'll hard fail soon.

So, here's what I've done:
- bought a new Macronix MX25L3205(A) chip,
- bought a USB based EEPROM burner (CH341A_SPI),
- used ROMtool to read my current Flash ROM to an image file,
- used flashrom to write that image file to the new Macronix chip,
- confirmed with MD5 checksums that old and new chip contents are identical

My question is: if I find the courage to solder the new chip onto the mainboard, will it just work?

I read somewhere that the original chip manufacturer warranted 100,000 write-cycles. Sounds like a lot, right?

But, after 12 years of constant use, where even volume changes are written to NVRAM, it's really not.

I'm just hoping to get a few more years of service from what is otherwise a really excellent Mac.
 

mbnt

macrumors member
Oct 22, 2003
47
29
NYC Metro Area
Before going nutty with hardware, I HIGHLY recommend you sit there and reset that NVRAM til it's blue in the face.

I'm NOT kidding.

I had a Mac that was really borked, and after 3 hours of "zapping PRAM," it came back to life.

Even if you have to tape down weights for it to bong for hours, do it.
 

tsialex

Contributor
Jun 13, 2016
13,216
13,393
Long story short: my mid-2010 cMP5,1 started exhibiting symptoms of Flash ROM corruption such as failure to find bootable USB, et al.

Using 4-bong NVRAM resets, ROMTool/UEFITool consistently shows 24KB of free space. But, I'm afraid it'll hard fail soon.

So, here's what I've done:
- bought a new Macronix MX25L3205(A) chip,
- bought a USB based EEPROM burner (CH341A_SPI),
- used ROMtool to read my current Flash ROM to an image file,
- used flashrom to write that image file to the new Macronix chip,
- confirmed with MD5 checksums that old and new chip contents are identical

My question is: if I find the courage to solder the new chip onto the mainboard, will it just work?

You just cloned any problems that your NVRAM volume currently has, but asnwering your question, yes, should work. This way you just solved the SPI flash memory problem, not the logical problems.

I read somewhere that the original chip manufacturer warranted 100,000 write-cycles. Sounds like a lot, right?

Nope, 100K cycles are for non-contiguous writes only, MacPro NVRAM volume is contiguous and will fail a lot sooner - but probably something else will fail on the backplane before the replaced SPI flash dies again.

But, after 12 years of constant use, where even volume changes are written to NVRAM, it's really not.

Even more so with what I just explained.

I'm just hoping to get a few more years of service from what is otherwise a really excellent Mac.

The way to go is flashing a fully updated never booted and reconstructed BootROM image.
 

tsialex

Contributor
Jun 13, 2016
13,216
13,393
Before going nutty with hardware, I HIGHLY recommend you sit there and reset that NVRAM til it's blue in the face.

I'm NOT kidding.

I had a Mac that was really borked, and after 3 hours of "zapping PRAM," it came back to life.

Even if you have to tape down weights for it to bong for hours, do it.

This is literally insane, doing what you suggested remove years of life from the SPI flash.
 
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ppinter1

macrumors newbie
Original poster
Sep 4, 2008
14
6
Yes, it wasn't clear from my post, but that's where I am now.

I did PRAM resets until it was stable again, with 24KB free space consistently reported by ROMTool/UEFITool for weeks now - I don't even adjust system volume anymore, but I'm afraid if the NVRAM chip is on its last legs, it'll be sayonara at an inopportune time (naturally).

I guess if that happens, I'll be looking at chip surgery anyway, but in a hard down/panic situation. I'd like to know if I risk chip surgery now, will the machine be fooled? Will NVRAM garbage collection work again/better?

Thanks for taking the time to reply.

Before going nutty with hardware, I HIGHLY recommend you sit there and reset that NVRAM til it's blue in the face.

I'm NOT kidding.

I had a Mac that was really borked, and after 3 hours of "zapping PRAM," it came back to life.

Even if you have to tape down weights for it to bong for hours, do it.
 
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tsialex

Contributor
Jun 13, 2016
13,216
13,393
Yes, it wasn't clear from my post, but that's where I am now.

I did PRAM resets until it was stable again, with 24KB free space consistently reported by ROMTool/UEFITool for weeks now - I don't even adjust system volume anymore, but I'm afraid if the NVRAM chip is on its last legs, it'll be sayonara at an inopportune time (naturally).

I guess if that happens, I'll be looking at chip surgery anyway, but in a hard down/panic situation. I'd like to know if I risk chip surgery now, will the machine be fooled? Will NVRAM garbage collection work again/better?

Thanks for taking the time to reply.
Cloning the BootROM to a new SPI solves only the SPI related issues, not the logical ones.
 

ppinter1

macrumors newbie
Original poster
Sep 4, 2008
14
6
The way to go is flashing a fully updated never booted and reconstructed BootROM image.
Hi Alex, I was hoping you'd chime in.

The vendor I bought the new chip from encoded my system serial number onto the chip at the correct location. I kept that ROM image, but it obviously wouldn't include any other data (e.g. ESN).

Is there any value in burning that virginal image to the chip? Will the machine get back on its feet? Or, am I looking at a 'BootROM reconstruction service'?

Muito obrigado senhor
 

tsialex

Contributor
Jun 13, 2016
13,216
13,393
Hi Alex, I was hoping you'd chime in.

The vendor I bought the new chip from encoded my system serial number onto the chip at the correct location. I kept that ROM image, but it obviously wouldn't include any other data (e.g. ESN).

Is there any value in burning that virginal image to the chip? Will the machine get back on its feet? Or, am I looking at a 'BootROM reconstruction service'?

Muito obrigado senhor
Seems you want to do it the correct way and get some more years of service from your Mac Pro, so, the way to go is with a clean-up, full upgrade and reconstruction of your own Mac Pro BootROM - with the real factory installed MLB SN/BD/HWC/GAID, the correct checksums and other minor things - not a BootROM image from another Mac that someone modified with your SSN.

I'll send you a PM about instructions/cost.
 
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tsialex

Contributor
Jun 13, 2016
13,216
13,393
This is really bad, probably the worst I remember, garbage collection failed a long time ago:

Screen Shot 2023-02-02 at 00.43.37.png
 

ppinter1

macrumors newbie
Original poster
Sep 4, 2008
14
6
To close this thread, I did have Alex perform a BootROM reconstruction service and my MacPro is now running perfectly.

I've burned his reconstructed BootROM image to a new Macronix chip, which I'll keep in reserve if the OEM chip fails.

For a machine built in August 2010, I'm grateful to squeeze a few more years out of this most excellent MacPro.

Thanks again, Alex!
 
Last edited:
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