Older Mac Pro Only Boots to MacOS Even if Windows is Selected

Hi, new trial user here. I just finished up refurbishing an older 2009 4,1 Mac Pro to the equivalent of a 2010 5,1 (EFI BIOS upgrade, SSD, etc)…I have an un-flashed EVGA/Nvidia graphics card in it so “Option” key & “select Windows” really isn’t an option for me…hoping to get Boot Runner to work but am having trouble getting the “Windows” selection/boot working. The machine boots back to MacOS/Boot Runner most every time. I say “most every time” because I swear that once I did have it working after switching the option for “Force Boot Option” to “Legacy”…I walked away and when I came the next day the same “boot loop” back to MacOS problem was back.

MasOS is High Sierra (10.13.5) and I have “SIP” disabled (the “csrutil enable -without nvram” command didn’t work on my system).
I have Windows 10 installed on a separate conventional drive and mounted as “BOOTCAMP”/“disk1s1”.
Windows 10 boots fine if I add a Mac flashed graphics card to the system and use the “Option” key at boot up.
The EFI BIOS is the equivalent of a 2010 Mac Pro 5,1 (2 CPU/12 core 32 gig. RAM, SSD boot drive-“disk2s1”).
I have the two volumes listed in “Volume & VM Config”.
The rest of Boot Runner appears to be working OK (marquee, pop-up config, etc.).
Windows 10 was installed from a DVD and is not “EFI Boot” (MBR boot I guess).

Help? Any suggestions? Thanks in advance.

As a test, what happens when you select the startup disk in System Preferences? Does the Windows volume show up there and can you select it? Does it boot successfully into Windows?


Hi Tim, I went to “Select Start-up Disk” in “Prefs” and I got a new error I haven’t seen before (last time I selected a start disk in Prefs was before installing Boot Runner, no error then)…the error is “You cannot change the start-up disk to the selected disk” (BOOTCAMP) “The bless tool was unable to set the current boot disk”. I went into the recovery partition/terminal and confirmed that SIP is still “disabled”.

Did you use WInclone to restore Windows, or was it installed via the installer? If it was via the installer, then there is something else going on since macOS is having trouble setting the startup disk. Can you tell me a bit more about how the system was upgraded?