MP 1,1-5,1 No Power on Mac Pro 4,1

[KingCornWallis]

Mac Pro is no longer turning on, story is about the exact same as this post.

I had experienced issues before, random shutdowns, the occasional useful error message, one I recall being about 'Sleep Wake Failure'. I began to think after that error message that it was related to the AirPort card failing, as I mis-wired an upgrade card and may have fried it. However, I would think that if it worked at all, it's clearly not fried.

So I am following the Minimum Configuration Testing steps in the Mac Pro Early 2009 Apple Technician Guide...I am at step 6 where I need to jump the SYS_PWR pads. Jumping them does nothing.

So...what died here...and how? The Backplane board or the PSU (that I meticulously Pixla-modded)? Can I test the PSU with a multimeter?

Thanks...

 

[tsialex]

Could be either one, test your Mac Pro with a known good PSU. It's a 12 to 13 years old Mac Pro, components have useful life.

PSUs can't be tested with a multimeter, or at least not without applying required load on each rail, results are not meaningful without load and you need to know what/how/where to measure.

 

[KingCornWallis]

Could be either one, test your Mac Pro with a known good PSU. It's a 12 to 13 years old Mac Pro, components have useful life.

PSUs can't be tested with a multimeter, or at least not without applying required load on each rail, results are not meaningful without load and you need to know what/how/where to measure.

I am back from the dead. Purchased a replacement PSU, and prior to performing the Pixla's mod on it I plugged it in as-is and ran through the Minimum Configuration Testing. Jumping the SYS_PWR pads proved fruitful.

I performed the Pixla's mod on the new PSU and installed it along with the CPU's, RAM, SATA SSD, PCIe NVMe SSD, Airport Card, and GPU. I booted into 10.14.6 on the SATA SSD with the RX Vega 64 and ran the machine overnight. No crash. The the system was complaining about an unrecognizable disk (Big Sur on NVMe on PCIe adapter). I noticed that performance was choppy/stuttery while using; Could drag a window or hover over a file and at times would take over a second to respond. After wiping the NVMe drive this issue seemed to disappear.

Thinking I was in the clear, I powered down and installed most of the rest of my components (Thunderbolt card, USB 3.0 Card, Optical Drive, Second SATA SSD). I then booted and downloaded OCLP and started downloading a Monterey Installer. 3/4 through the system shuts down. It tries to immediately restart, but no chime or video.

Subsequent attempts to boot result in the same...system on for a few seconds with no chime or video...then off...then an immediate second attempt.

Deep PRAM reset and SMC did not help. System not even responding much now.

Performed Minimum Configuration Testing again...and now jumping the SYS_PWR pads does not do anything.

Such strange behavior. Is this proven to be the backplane board at this point?

 

[Matty_TypeR]

There is no reason as to why PSU's fail, even the newer one you purchased 2nd hand might have failed when fully loaded. Apple had 2 brands of PSU for the Mac pro 4.1 5.1 Delta electronic's version, and AC bell version. If you purchase another try and get a Delta electronics PSU they are the better out of the 2 PSU's apple used.

Thats not to say either cant fail, but the delta is a better design and better components used. also run cooler than the AC bell variety.

As you stated before your Mac came back from the dead with a replacement PSU there is nothing to say the replacement PSU didn't fail as well to give you the same as before.

 

[KingCornWallis]

There is no reason as to why PSU's fail, even the newer one you purchased 2nd hand might have failed when fully loaded. Apple had 2 brands of PSU for the Mac pro 4.1 5.1 Delta electronic's version, and AC bell version. If you purchase another try and get a Delta electronics PSU they are the better out of the 2 PSU's apple used.

Thats not to say either cant fail, but the delta is a better design and better components used. also run cooler than the AC bell variety.

As you stated before your Mac came back from the dead with a replacement PSU there is nothing to say the replacement PSU didn't fail as well to give you the same as before.

Both PSU's were Delta Electronics. While I can't vouch for the replacement PSU, the original PSU seemed to work fine until the Pixla's Mod. And I have done absolutely nothing intensive on this computer...so unless by full load you mean an idling Vega 64 drawing its normal power via the mod, it has never been stressed.

With that being said though, I have killed 2 PSU's. Is it possible I have done the mod incorrectly? It's unlikely its pure coincidence at this point.

I have reused the dual 8-pin breakout cable for both PSU's. I using the Spades + T-Taps method (HouseOfMoth). The only thing I can see as a potential issue is the wire inside some of the spades are 'loose' but still making good contact from what I can tell. Could this short and FRY a PSU?

 

[Matty_TypeR]

Seem's very strange that both PSU's have failed after you have done the Pixlas mod. I would check your connections as that spade connection has to go into the female part correctly, it can feel it has but it might not have done.

Check all wiring and perhaps if you get another PSU run it with out mod with older GFX card to see if it remains stable.

 

[KingCornWallis]

It is time again for my annual attempt at repairing this Mac Pro. I have 2 new (to me, and 'tested working' by seller) Apple PSU's to try out. As before, I have installed the new PSU along with nothing but the basics for a working computer and it did not boot.

Performed Minimum Configuration Testing once again...and jumping the SYS_PWR pads does not do anything just like when I left off. (Half tempted to solder on a button at this point LOL...really curious as to why so many diagnostic LED's and buttons weren't added to my board).

So, is it the backplane board? It's like $50 last I checked...just will be a nuisance swapping out.

 

[flat4]

I am back from the dead. Purchased a replacement PSU, and prior to performing the Pixla's mod on it I plugged it in as-is and ran through the Minimum Configuration Testing. Jumping the SYS_PWR pads proved fruitful.

I performed the Pixla's mod on the new PSU and installed it along with the CPU's, RAM, SATA SSD, PCIe NVMe SSD, Airport Card, and GPU. I booted into 10.14.6 on the SATA SSD with the RX Vega 64 and ran the machine overnight. No crash. The the system was complaining about an unrecognizable disk (Big Sur on NVMe on PCIe adapter). I noticed that performance was choppy/stuttery while using; Could drag a window or hover over a file and at times would take over a second to respond. After wiping the NVMe drive this issue seemed to disappear.

Thinking I was in the clear, I powered down and installed most of the rest of my components (Thunderbolt card, USB 3.0 Card, Optical Drive, Second SATA SSD). I then booted and downloaded OCLP and started downloading a Monterey Installer. 3/4 through the system shuts down. It tries to immediately restart, but no chime or video.

Subsequent attempts to boot result in the same...system on for a few seconds with no chime or video...then off...then an immediate second attempt.

Deep PRAM reset and SMC did not help. System not even responding much now.

Performed Minimum Configuration Testing again...and now jumping the SYS_PWR pads does not do anything.

Such strange behavior. Is this proven to be the backplane board at this point?

TL;DR
If you have a different tray, try it as it would rule out the backplane if it works.

Had a similar problem no chime nothing, had spare tray with single cpu and it ran for a week no issues.
On the dual tray I Re-pasted the cpu, north bridge. etc. cleaned the tray install it back and it worked