PCIe card Windows conflict

[natjonesart]

Hey guys, I have a PCIe Sata III adapter card with a Samsung SSD on it and my 5,1 goes to black screen with flashing prompt whenever I try to boot into Windows 10. If I remove the card Windows boots fine. They say the card is Windows compatible. Is this a driver issue? Can I make this work? I rarely use Windows but I would rather not have to remove a card any time I do need to.

Here is a link to the card
http://www.ebay.ca/itm/112249525994?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

[ActionableMango]

Did you install Windows in EFI mode instead of BIOS? If so, maybe that.

 

[owbp]

Almost certain that ActionableMango is right. Flashing prompt means that Win EFI can't boot because it found some sort of BIOS in PCIe slot.
For the last few days I'm reading just about that.

 

[ActionableMango]

I've struggled with this myself in the past. I'm not 100% sure what's going on, so this is only theory.

I think the computer sees a BIOS card (in this case your PCIe SATA III card) and so activates the Compatibility Support Mode for BIOS booting. Then at boot time it ignores the bootable EFI partition because it is in BIOS mode, and so it tries to boot the NTFS main partition instead. But the NTFS main partition is not bootable in an EFI installation, so you get the black screen with the not bootable disk error.

Can I make this work?

Again I'm not 100% sure about your problem, especially since you haven't mentioned if Windows is a BIOS or EFI install. But in my case I installed rEFInd and it worked for me.

Whereas the Apple ALT/OPTION boot choice has a very limited selection (and in this case an incorrect selection), rEFInd has no problem showing all of them, including the Windows EFI boot partition. In my case if I manually select the EFI boot partition, everything works.

 

[natjonesart]

Thanks for the replies guys. I ave to be honest, this is my first time installing windows on a Mac and I truthfully don't know which mode it is. I am looking into rEFInd right now, they have info there that should help me find out.
[doublepost=1486184571][/doublepost]I have more info. Checking in MSINFO32 My Windows Bios is Legacy

 

[ActionableMango]

Well there goes that theory.

 

[Auggie]

I'm curious if this is why my Sonnet Tempo SSD Pro Plus will not boot into any flavor of Windows regardless of source (USB flash installer, Windows DVD, Boot Camp, triple-boot Windows-only MBR drive) in my 4,1; I have to physically remove it from its slot to run Windows.

Although Windows seems to boot fine with the card in 5,1 I yanked it out of that when I discovered I couldn't load the startup boot picker window, which I need because when I'm booted into Yosemite the Startup Disk preferences pane isn't able to detect and list any Core Storage volumes (I have two) so I have to get to the boot picker window after a Yosemite session.

 

[haralds]

Have you tried a safe boot?

 

[natjonesart]

Have you tried a safe boot?

Sorry, new to all of this. How would I go about that in a dual boot system? When would I press F8?
[doublepost=1486492429][/doublepost]

I'm curious if this is why my Sonnet Tempo SSD Pro Plus will not boot into any flavor of Windows regardless of source (USB flash installer, Windows DVD, Boot Camp, triple-boot Windows-only MBR drive) in my 4,1; I have to physically remove it from its slot to run Windows.

Although Windows seems to boot fine with the card in 5,1 I yanked it out of that when I discovered I couldn't load the startup boot picker window, which I need because when I'm booted into Yosemite the Startup Disk preferences pane isn't able to detect and list any Core Storage volumes (I have two) so I have to get to the boot picker window after a Yosemite session.

Not sure if our issues are related, but my machine is a 4,1 flashed to 5,1

 

[two-mac-jack]

I just had similar problems (black screen with flashing cursor) trying to boot into Windows 10 on my cMP 5,1 -- fixed by installing rEFInd.

Previously it worked fine (most of the time) using the Option key after the boot chime and selecting the Windows drive. But a few days after moving my Windows SSD from the optical bay to drive bay 2, and adding a 2nd GPU, I noticed Windows would no longer load. At first I assumed something had corrupted the drive, and started researching Windows Recovery options. Luckily I found this thread!

Just as users natjonesart and Auggie observed, if I removed the PCIe SSD card holding my OS X boot drive (and two other drives), suddenly I could boot into Windows no problem -- so clearly the drive was fine.

In a different thread, ActionableMango described 6 possible ways of fixing this problem (thank you!), and ultimately I took the suggestion to install rEFInd as an alternative boot manager. I took the easy path, using the provided "refind-install" script, and it just worked -- including fixing my problem with booting to Windows 10. Apple's built-in option key boot screen is still available so you aren't losing anything by installing rEFInd, and it's clearly a better boot manager that is faster and fully configurable. It saved me a day of investigating arcane Windows boot tech, so I made a donation.

In El Capitan and above, you must temporarily turn off SIP before installing rEFInd, then turn it back on. Speaking of which, there is a convenient feature in rEFInd you can enable in the refind.conf file that lets you toggle SIP on and off, without having to boot into Recovery mode.

I noticed that the rEFInd boot screen labels my Windows drive as "(Legacy)", which I think means it is configured for BIOS rather than EFI boot. I did a clean install of Windows 7 on this drive about 3 years ago, then upgraded it to Windows 10 late last year. Perhaps if I had done a clean install of Windows 10 I wouldn't have encountered this problem.