Mac pro, Win 10 boots only on drive bay 1 and 2, 3 and 4 can't boot win 10

[chris-snd]

Oke,

I have the strangest thing, scenario:

2014:
Mac pro 3.1 with it's original ati graphics card, always running fine and upgraded towards el capitan in the years coming.
Did not use windows or anything on it until 2021.


2021:

I upgraded my mac pro 3.1 running el capitan with a radeon 5770 because i needed the display port for a new monitor (ultra wide screen)

After the upgrade to the radeon 5770, i installed win 10 with a dvd on a ssd in drivebay 3 in legacy mode. No problems. Always running fine, can boot with alt in mac os (ssd bay 1) or win 10 (ssd bay 3)

Drive bay 1 ssd El capitan,
Drive bay 2 harddisk data for el capitan
Drive bay 3 ssd win 10 legacy
Drivebay 4 harddisk data for win 10


2023,

I bought a mac pro 5.1 with a gtx 680

Installed mojave on a nvme drive + simple pcie card on pcie slot 3,

Tried installing win 10 on a ssd in drivebay 3, problems and more problems, it just would not boot win 10, until i tried the win 10 ssd in bay 1 and 2, then win 10 would boot!

The mac pro 5.1 can read any harddrive in any drivebay in win and mac os, but it just can't boot win 10 in Bay 3 and 4.
So at that point, i thougt it's a limitation that only affects the mac pro 5.1, and not the mac pro 3.1.
I could live with that.



Oke, 2023 july

I upgraded the mac pro 5.1 with a radeon vega 56, so i have a spare gtx 680.

I upgraded my old mac pro 3.1 with still the same config as in 2021 with the gtx 680 witch I pulled from the mac pro 5.1

With the gtx 680 in the mac pro 3.1 all is running good,

boot mac os El capitan from the ssd in drive bay 1 is working fine.

Boot win 10 from the ssd in drivebay 3 is working fine!


So no problems here, but here it comes.


I took every drivebay out the mac pro 3.1, except drivebay 1 with the ssd. Did the nvram reset 3 times, and started installing a fresh copy of mojave with the dosdude1 patch on the now formatted ssd. All is fine, a working mojave os in drivebay 1, and the old windows 10 ssd in drivebay 3 wich hasn't change untill 2021 is still working.

Ok, from here, I swapped the ssd,s. The win 10 is a 128 gb ssd, the mac os is a 256 gb ssd.

So i started from scratch.

First I installed Catalina on the ssd in drivebay 1, no problems.

After that i installed win 10 on the ssd in drivebay 3,.... I installed it like 6 times. The install procedure gives no problems. But booting afterwards, it just won't boot. Finally I discovered when I put the fresh installed win 10 ssd in drivebay 1 or 2, win 10 will boot and leads me thruw the win 10 post install options.

So, as of now I'm really confused. Why won't win 10 suddenly boot in drivebay 3 and 4?

With the mac pro 5.1 i thougt it was a hardware limitation (strange but what do i know) but now with the mac pro 3.1 i have the same problem so there is something going on here.

OK some more testing,

I have a second spare untouched mac pro 3.1 with El capitan running on a old spinning disk with the old radeon 5770 in it. So i tried my win 10 ssd in drivebay 3 in that mac.
Same problems, it won't boot.

So now I'm thinking this problem with win 10 not booting in drivebay 3 and 4 is related to the vidcards change, i know it's strange, but all this only happened after installing win 10 with a gtx 680 and a vega 56 no matter which mac pro.

When I installed win 10 on a ssd in drivebay 3 in 2021 while running the radeon 5770 i didn't have problems.


Anyway,

I can read harddisks and ssd's in all drivebays in osx and win 10, also the osx boot ssd does boot in all drivebays. it's just that drivebay 3 and 4 won't boot a windows 10 disk.

So in the coming days I will do some more testing with my untouched spare mac pro 3.1, equipped with the radeon 5770. ill do a fresh win 10 install on a ssd in drivebay 3 while drive 1 is occupied with the old el capitan spinning hard drive.

Really can't wrap my head arround this.

Anyone knows about this problem/bug?

 

[DeltaMac]

What prevents you from simply leaving the Win10 boot drive in slot 2?

 

[chris-snd]

What prevents you from simply leaving the Win10 boot drive in slot 2?

Your right, nothing prevents me. And that's what I did with the mac pro 5.1, i thougt it was a limitation and there was no other option, so i thought.

But now i know there is something going on and i want to know why.
Why does bay 3 and 4 behave different now and not back then? It's affecting both 3.1 and apperently the 5.1.

Doesn't that bother you? When you have equipment and suddenly it doesn't function like it did before?

 

[DeltaMac]

It's related to the change of graphics card. I would suspect that the graphics card (somehow) modifies the SATA bus, so it will no longer allow booting from slots 3 or 4. So, storage is fine, just not booting.

 

[chris-snd]

Yeah it seems like it, strange.

Anyway, I did a new test

I installed the old radeon 5770 in the mac pro 3.1. After that i installed win 10 again on ssd in bay 3.

Same problem, no booting. When I put that ssd I just installed win 10 on in bay 1 or 2 it does boot.

So new test:

I'm now installing win10 on the original ssd (128 gb kingston) which did work with win 10 in bay 3.

 

[bobcomer]

Yeah it seems like it, strange.

Anyway, I did a new test

I installed the old radeon 5770 in the mac pro 3.1. After that i installed win 10 again on ssd in bay 3.

Same problem, no booting. When I put that ssd I just installed win 10 on in bay 1 or 2 it does boot.

So new test:

I'm now installing win10 on the original ssd (128 gb kingston) which did work with win 10 in bay 3.

It sounds like a BIOS issue to me and probably can be changed. (boot order and boot settings) I never used a Mac Pro, but if a Windows PC did that...

Do those new video cards, per chance, have a thunderbolt port or other bootable port on them? That could be taking up a slot in the boot table and confusing the partition scheme.

 

[chris-snd]

Oke the kingston 128 gb ssd with win 10 does work in bay 3 and 4!




I think i maybe have found what is causing the problem.

Every ssd that had osx installed in the past and thus was formatted with Guid doesn't work anymore when formatted with MBR and a win 10 legacy install in bay 3 and 4.

New ssd's and ssd's wich where only used with a win boot and thus only a MBR format will work with a win 10 install in every bay.

So i think that when ever a new ssd is formatted with a guid boot it doesn't work anymore in bay 3 and 4, even if you have afterwards format it with MBR.

Now i also think i know why the mac pro 5.1 doesn't boot win 10 in bay 3 and 4. The ssd with win 10 in it had osx installed in the past.


How is that possible and why does it only affect bay 3 and 4?

Seems to me that there must be a way to "reset" a ssd so I can use it again in bay 3 and 4.



But it gets weirder, now the kingston...

I formatted it a few days ago with mac os extended journalled, only to find out i can't install Catalina. So i reformatted it to apfs, and successfully booted Catalina with it in the mac pro, so a bit strange that this ssd now still works with win 10 on it in drivebay 3 and 4.

So i thougt ok, lets format a not working ssd with apfs, and then format/convert it back and install win 10 on it, nope doesn't work.

 

[bobcomer]

Seems to me that there must be a way to "reset" a ssd so I can use it again in bay 3 and 4.

Interesting problem!

I only know a Windows way to reset a "disk",

Using the utility diskpart

>list disk

>
Disk ### Status Size Free Dyn Gpt
-------- ------------- ------- ------- --- ---
Disk 0 Online 465 GB 0 B *
Disk 1 No Media 0 B 0 B
Disk 2 Online 1907 GB 0 B *
Disk 3 Online 3726 GB 127 MB *

> select disk 3

Disk 3 is now the selected disk.

>clean
>convert mbr

>exit

You can do this with booting from a install USB by hitting shift-F10 to open a command prompt. The disk number from you would most likely be different.

 

[chris-snd]

Interesting, used the command prompt disk part cleaning a lot for "dead" usb sticks that came alive again so that could be of some help i guess.
I will try that the next time! Maybe there is some osx "residue" that can't be removed with formatting.

The Vid cards don't have any bootable port.

Thanks so far!

 

[Dayo]

Maybe there is some osx "residue" that can't be removed with formatting.

You can try to "Nuke" such problem disks before reformating.

In Mac OS Terminal:
Type "diskutil list" and look for the Disk ID; which will be a "/dev/disk#" string (See image linked below)
Type "sudo gpt destroy /dev/disk#"

https://forums.macrumors.com/attachments/img_03-png.944815

You end up with the disk as was before it was ever initialised.
You can then mount and use Disk Utility to format.
Make sure you select the right Disk ID!