Mac Pro 4,1 no chime or video after dual CPU upgrade

Question

Level 1

4 points

Mac Pro 4,1 no chime or video after dual CPU upgrade

I recently purchased a Mac Pro 4,1 off of Facebook Marketplace listed as “untested”. I get it home, plug it in, and get a CPU error light on the board (single cpu board). I wanted to upgrade it to a dual anyway so I just bought a dual board that included CPUs and swapped over the RAM after repasting the CPUs. After this, I plugged everything in and now the fans turn on but I don’t hear a chime and I don’t get any video output. What should I do?

The specs are:

2x4GB Crucial ECC DDR3 memory sticks (one in each bank)

2x Xeon E5520 processors

Nvidia GT120 GPU

No storage installed currently

What I’ve tried:

Reseating just about everything

Resetting PRAM and SMC

Moving the GPU to a different slot

Swapping around memory sticks/using different sticks

Adjusting tightness of CPU heatsinks

Removing any extra PCIE cards

Replacing PRAM battery

The diagnostic top lights, in order, show:

nothing (CPU A)

nothing (CPU B)

green (PSU PWR)

amber (5V STBY)

the bottom diagnostic lights, in order, show:

green (SYS PG)

green (EFI PWR)

green (GPU OK)

Posted on May 9, 2026 6:39 PM

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Answer 1

mellishr18 Author

Level 1

4 points

May 10, 2026 8:17 AM in response to Grant Bennet-Alder

Looks like the CPU riser board is the culprit. I tried it with only CPU A installed and it chimed, so I’m thinking there’s something wrong with either socket B or it’s installed processor.

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Answer 2

May 10, 2026 8:10 AM in response to mellishr18

You are changing far too many things at once.

to make progress, you will likely need more 'known-good' parts.

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Answer 3

mellishr18 Author

Level 1

4 points

May 10, 2026 10:57 AM in response to Grant Bennet-Alder

When I said “riser board”, I was referring to the processor tray or shelf or whatever you want to call it. No error indication coming from the power indicator, but I got it to chime with a single processor installed.

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Answer 4

May 9, 2026 8:27 PM in response to mellishr18

Here is the Apple Service Guide for the Mac Pro (early 2009):

http://tim.id.au/laptops/apple/macpro/macpro_early2009.pdf

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Answer 5

May 10, 2026 8:07 AM in response to mellishr18

You may also benefit from referencing Greg Gant guide about upgrading Mac Pro entitled

The Definitive Classic Mac Pro (2006-2012) Upgrade Guide

Novice users should never attempt its procedures. Because it contains descriptions of things that might damage your computer or your person, direct links to it are often removed.

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Answer 6

May 10, 2026 8:32 AM in response to mellishr18

<< CPU riser board >>

WHAT?

That model has a slide-out shelf with the processor(s) on it. There is no riser-board.

the 2009 model used lidless processors on the dual-socket processor shelf.

the 2010/12 models used standard lidded processors or the dual-socket processor shelf.

both used standard lidded processor on the single-socket processor shelf.

also, observe the power indicator light carefully. some fundamental errors will blink a "help-me" code.

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Answer 7

May 10, 2026 11:57 AM in response to mellishr18

The chime is generated in Software. It can only occur when the Power-On Self Test passed. That tests the processor, all RAM present (including Error-correcting code logic) and simple functions of the mainboard, and found none appeared to have GROSS issues.

You don't have bad RAM

you don't have bad power

your don't have bad mainboard

did the display light up?

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Answer 8

May 10, 2026 10:44 AM in response to Grant Bennet-Alder

Grant Bennet-Alder wrote:

You may also benefit from referencing Greg Gant guide about upgrading Mac Pro entitled

The Definitive Classic Mac Pro (2006-2012) Upgrade Guide

Was this meant to be a link?

I think the forums have developed yet another problem here since you can see my link lost its hyperlink attribute, but fortunately the link & link title were the same for mine.

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Answer 9

May 10, 2026 11:02 AM in response to mellishr18

The initial "chime" sound is generated in software when your Mac passes the Power-On Self Test. If the chime occurs and/or startup continues, your Mac is working. The screen should light up and draw a blank gray screen.

Then on to the Disk Drive.

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Answer 10

May 10, 2026 10:57 AM in response to HWTech

That is not a malfunction.

The link has previously been removed, so I simply posted the title above.

https://blog.greggant.com/posts/2018/05/07/definitive-mac-pro-upgrade-guide.html

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Answer 11

mellishr18 Author

Level 1

4 points

May 10, 2026 11:13 AM in response to Grant Bennet-Alder

The chime wasn’t occurring before, I’m saying that this issue is most likely resolved as the processor tray seems to be faulty.

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