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Mac Pro 5,1 and Windows 10 boot issue

Hi all,

I am having problem with my Mac Pro 5,1 recently. I have El Capitan on Bay 1, Windows 10 on Bay 2, Bay 3&4 are RAID 1 for Mac data. Normally I hold Alt to boot into Windows, but after El Capitan installation it doesn't work anymore. Windows boot returns a black screen. So my current work-around is to take out Bay 1 (El Capitan) when I want to work in Windows, and Windows would boot fine. I've never had this problem before with Yosemite as such.

Has anyone here encountered the same issue that could give me some pointer?

Many thanks for your helps in advance.

Mac Pro, OS X El Capitan (10.11), null

Posted on Oct 11, 2015 3:49 PM

32 replies

Loner T

Level 9

59,471 points

Oct 13, 2015 11:47 AM in response to Tran Hoang Long

Windows Defender should not cause such problems. Are you able to boot in Windows Safe Mode?

Oct 13, 2015 11:58 AM in response to Loner T

Yes I was in safe mode twice, after reseting SMC and NVRAM. Is there anything I should do in there because I normally just go straight to shut down (instead of Troubleshooting), then reboot into Windows

Loner T

Level 9

59,471 points

Oct 13, 2015 12:06 PM in response to Tran Hoang Long

Yes, shut down and try. If it does not work, we can diagnose it further.

Oct 13, 2015 12:16 PM in response to Loner T

I really cannot thank you enough for your help since yesterday, Loner T! So many helpful people on this forum.

So, what happened with my mac so far in the last 30 mins:

. I went into W10 Safe Mode, shut down.

. Hold alt, rebooted into W10 fine.

. Restart, hold alt to boot into ELC, all fine.

. Restart, hold alt to try to boot into W10 again, black screen of death. ARGHHH!

. I think after booting into ELC, it kills W10 boot for some reasons (anything to do with SIP?)

Loner T

Level 9

59,471 points

Oct 13, 2015 12:20 PM in response to Tran Hoang Long

It seems to be an issue with the bless command. Can you test the following sequence?

1. Boot into ELC, without any changes to SIP.

2. Go To System Preferences -> Startup Disk.

3. Unlock with your password, select Bootcamp.

4. Select W10 and Restart.

5. If you see any error messages, check Application -> Utilities -> Console logs for any issues with the W10 partition.

Let us try and narrow it down.

Oct 13, 2015 12:33 PM in response to Loner T

I followed the sequence, when it got to Windows, it said "No bootable device – please insert a boot drive and press any key to continue". Which part of the Console log would you like me to post?

Loner T

Level 9

59,471 points

Oct 13, 2015 1:15 PM in response to Tran Hoang Long

Check for any ntfs, bootcamp or bless related messages.

Oct 13, 2015 1:19 PM in response to Loner T

Thanks, I've done searches for all of these keyword but apparently there's none. Would there be a log in Console if I booted into Windows outside of Mac thou? I thought Console only records what happening in Mac environment?

Loner T

Level 9

59,471 points

Oct 13, 2015 2:48 PM in response to Tran Hoang Long

Tran Hoang Long wrote:

Thanks, I've done searches for all of these keyword but apparently there's none. Would there be a log in Console if I booted into Windows outside of Mac thou? I thought Console only records what happening in Mac environment?

The console would have entries if you used System Preferences -> Startup Disk. If you used Alt/Option, then Console will have no record.

Oct 13, 2015 2:53 PM in response to Loner T

Ah I see. So that's what happened, I followed exactly as you specified, it said "No bootable device,... etc" when attempting to restart into windows via System Prefs / Startup Disk. Then I shut it down, boot back into ELC via Alt, fired up Console then there was nothing. If I didn't press Alt, Windows would just be the default boot drive.

Oct 14, 2015 12:41 PM in response to Loner T

Hi Loner T,

Is there anything else you can suggest to diagnose my drives since the last method (Console log) didn't work? Thanks a lot!

Loner T

Level 9

59,471 points

Oct 14, 2015 3:31 PM in response to Tran Hoang Long

Do you have a spare SATA disk on which you can install Mavericks or Yosemite?

Oct 14, 2015 3:47 PM in response to Loner T

I got Snow Leopard partition on the same drive as ELC. Would it help? The only spare drive I have is an external USB, is it ok? I have Yosemite DMG handy.

Loner T

Level 9

59,471 points

Oct 14, 2015 3:55 PM in response to Tran Hoang Long

Run a SMC and NVRAM Reset and shutdown the MP. Remove the ELC disk, install Yosemite on the external USB partition (you do not need to erase the disk).

Oct 14, 2015 3:57 PM in response to Loner T

Sure, I'll do that as soon as I can then get back to you. Many thanks for your help!

Mac Pro 5,1 and Windows 10 boot issue