How to install Windows 10 on Mac with A Flashed AMD Radeon HD7950 GPU

[HandsomePixel]

TL;DR How to install Windows 10 on Mac with Flashed AMD Radeon HD7950

Due to the sheer frustration this installation has been giving me, I caved and decided to ask if any of you can help me with this.

I am trying to install Windows 10 on my Mac Pro which was bought maxed out (2 quad core xeon processors, 32GB of RAM, plus a 480GB SSD as the Mac boot drive).
Fast forward a couple of years, and I decide to upgrade the GPU for video editing, and found the AMD Radeon HD 7950 (Not the Sapphire/Official version), which was flashed from the seller on eBay to have the boot screen functionality on Mac (the menu to choose what boot drive, recovery mode, etc.).

Now to the problem.
I burned the Windows 10 ISO to a DVD (couldn't boot AT ALL from "burning" the ISO to a usb stick).
After insterting/leaving the DVD disc inside, turning off the computer, turning it back on while holding ALT/Option key, and finally choosing the disc that says "EFI" (black screen as well when choosing "Windows"), the Windows 10 logo would appear for a couple of minutes and then an error would show saying "Your PC needs to be repaired".

What's mind-boggling for me is that I tried all of these exact steps on another Mac Pro that doesn't have an upgraded GPU, just the one it came with, and it worked! Windows installed on it and booted and everything!

I've come across a few threads about people having very similar issues where they upgrade the GPU (although all of them state that they were using the PC variant of the card without being flashed (losing the boot menu and other things every time they boot up their computer which I use))
From what I could understand from all of these threads is that the problem resides in Windows booting in EFI mode when their card doesn't support it?
I just want to run Windows for games, and that's it.
Too much trouble trying to use Wine or PlayOnMac while trying to install lots of libraries and such just to play some games (plus many more that aren't supported.)
Really appreciate it if someone could help.

 

[crjackson2134]

I recommend you use bootcamp assistant. Also go to the Apple support page for install instructions

If you want to install without it, try this...

Put the dvd in the drive. Power off the computer, the power on while continuously holding the “C” key down.

I think you will be able to install in legacy mode. Oh yea, Windows is generally easier to install initially when putting it on a drive in bay1.

Give it a go and see what happens. I’m booting Win10 with an EFI Flashed HD 7970 and all works perfectly.

 

[h9826790]

The 7950 Mac EFI is NOT compatible with the Windows 10 EFI mode.

The solution is simple, install Windows in legacy mode.

You can either choose the non EFI disc icon at boot manager. OR simply holding "C" to boot to the disc.

And then follow the on screen instruction to finish the Windows 10 installation.

 

[HandsomePixel]

The 7950 Mac EFI is NOT compatible with the Windows 10 EFI mode.

The solution is simple, install Windows in legacy mode.

You can either choose the non EFI disc icon at boot manager. OR simply holding "C" to boot to the disc.

I have already mentioned in my post that when I go the boot menu and select the disc that simply says "Windows" (NOT the EFI option), the screen turns black and no input is working.
But when I boot off the other disc option that says EFI", the Windows logo at least appears!
But then this error shows up immediately after
And then follow the on screen instruction to finish the Windows 10 installation:

 

[crjackson2134]

I have already mentioned in my post that when I go the boot menu and select the disc that simply says "Windows" (NOT the EFI option), the screen turns black and no input is working.
But when I boot off the other disc option that says EFI", the Windows logo at least appears!
But then this error shows up immediately after
And then follow the on screen instruction to finish the Windows 10 installation:

Yes, you mentioned you booted but you were going through the boot manager. That means you were using the EFI produced screen.

Try booting directly to the DVD by the method above (from a powered down state, holding the “C” key). This may give you better results.

 

[two-mac-jack]

I had the same kind of problems getting Win10 installed on my upgraded cMP 5,1 with the same specs as yours -- but with a R9 280X (7970) flashed by an eBay seller.

I spent days reading threads here about how to do an EFI Win10 install but nothing worked.

I gave up and finally had success installing in Legacy mode. I removed ALL drives from the machine except for the one to receive Windows, booted from the Win10 DVD I burned from the Microsoft ISO I downloaded, and let it install in Legacy mode. Then installed BootCamp drivers after Windows was running.

Like you, USB boot/install would NOT work at all on my machine.

One additional note: after swapping GPU cards and moving the Windows drive from my optical bay to one of the drive bays, Windows failed to boot -- it would go to the empty black screen with blinking white cursor. I tried rEFInd (which is fantastic, much better and faster boot experience), and messing around with Windows bootrec and bcdedit, but no luck. So I put my Windows SSD (EVO 840) back in the optical drive bay and have had no more problems.

 

[HandsomePixel]

Ok, I just finished shutting down the mac, turning it back on while holding down the C key, and it did boot straight to the DVD, but the exact errors showed up again.
I also repeated these steps while the disc was both in the upper and lower optical drive bays.
I ALSO redid all of this using a Windows 8.1 installer that I burned to another DVD, and the exact same blue screen error shows up, but instead of saying "...0xc0000255", the error for the Windows 8.1 was ..."0xc000000001".

Thank you all for your help anyway, at least I'm gaining knowledge on new things I never even know (like quick booting to a DVD installer by holding down the C key)
Hopefully one of you know a solution to this strange issue?

 

[crjackson2134]

Ok, I just finished shutting down the mac, turning it back on while holding down the C key, and it did boot straight to the DVD, but the exact errors showed up again.
I also repeated these steps while the disc was both in the upper and lower optical drive bays.
I ALSO redid all of this using a Windows 8.1 installer that I burned to another DVD, and the exact same blue screen error shows up, but instead of saying "...0xc0000255", the error for the Windows 8.1 was ..."0xc000000001".

Thank you all for your help anyway, at least I'm gaining knowledge on new things I never even know (like quick booting to a DVD installer by holding down the C key)
Hopefully one of you know a solution to this strange issue?

I don't know what else to try at this point other than a different video card. Sorry it's not working out for you.

I had a hard time installing too. I ended up pulling ALL drives from my system except 1 rotational drive installed into DriveBay1. It finally installed properly but it was a frustrating affair.

After the install finished, and all updates were applied, and Win was tested for a while, I cloned the drive (using Winclone) to an SSD and it's worked flawlessly since. I keep both an image of the clean install, and an updated image of current system archived so I don't have to go through that again.

Moving drives & location of drives has not been a problem for me since initial install.

I wish you luck, but I'm out of ideas at the moment.

 

[bookemdano]

I'm wondering what method you are using to make your DVD(s). Are you using the Microsoft-supplied Media Creation Tool or are you using some other method?

If you aren't using the MCT then you should definitely try that.

I wonder also if different versions of Win10 (there have been several updated releases in the last three years, including one this past April) could have an effect on the install process on the cMP. You could try finding older ISOs (I'd especially try the original RTM release) just to rule out issues caused by MS changing something in their install ISO.

And did you follow two-mac-jack's suggestion of pulling all other drives in this latest test? Is the drive you want to install on completely wiped blank of partitions? If not then you might want to try that.

Does your 7950 not have the switch on it to swap between BIOS 1 and BIOS 2? If it does have the switch (you can google 7950 BIOS switch to see example photos) you should try to toggle it to the other position to see if that gets you anywhere.

If still no go then it may have something to do with the EFI that got flashed on there. I have no idea how many different ones are floating around out there, but that could easily cause some of these issues.
[doublepost=1528739920][/doublepost]Other suggestions:

Maybe focus more on the "Windows" boot option (that gives you the black screen) instead and see if you can get a screen image. Are you using DisplayPort on the 7950? If so, can you try HDMI or DVI (if your card has those outputs) to see if you get a different result? If you have access to this other Mac Pro and can pull its stock card and temporarily install in your Mac Pro just for the install process then maybe that would work too (or alternatively, move your desired install drive temporarily to the other Mac Pro, install Windows on it there, and then move that drive back to your Mac Pro with the 7950.

Where there's a will there's almost always a way.

 

[HandsomePixel]

I'm wondering what method you are using to make your DVD(s). Are you using the Microsoft-supplied Media Creation Tool or are you using some other method?

I actually used 2 different methods of installing the Windows 10 Installer on 2 separate DVDs, one with the dd command (I'm just used to doing that with Linux ISOs) and the other with the Etcher program (although it warns me that it needs special processing to make the drive bootable, which is half-true?).

If you aren't using the MCT then you should definitely try that.

I'll add it to the list of ways

I wonder also if different versions of Win10 (there have been several updated releases in the last three years, including one this past April) could have an effect on the install process on the cMP. You could try finding older ISOs (I'd especially try the original RTM release) just to rule out issues caused by MS changing something in their install ISO.

On the Microsoft site to download Windows 10, it said something similar to download the Anniversary Update as the installer, which I did, and then upgrade to Creators thereafter (don't plan to though )

And did you follow two-mac-jack's suggestion of pulling all other drives in this latest test? Is the drive you want to install on completely wiped blank of partitions? If not then you might want to try that.

Yes, I pulled out ALL of the drives, including the macOS SSD, and only leaving the dedicated HDD for the Windows 10 Installer

Does your 7950 not have the switch on it to swap between BIOS 1 and BIOS 2? If it does have the switch (you can google 7950 BIOS switch to see example photos) you should try to toggle it to the other position to see if that gets you anywhere.

Nope, it's just a plain old AMD Radeon HD 7950 made specifically for PC that has been flashed by the eBay seller

If still no go then it may have something to do with the EFI that got flashed on there. I have no idea how many different ones are floating around out there, but that could easily cause some of these issues.

Well that stinks, then I simply can't boot Windows without the error then.

Maybe focus more on the "Windows" boot option (that gives you the black screen) instead and see if you can get a screen image. Are you using DisplayPort on the 7950? If so, can you try HDMI or DVI (if your card has those outputs) to see if you get a different result?

Perhaps I wan't clear enough, I DO "boot" from the DVD, the Windows 10 logo DOES show, but then I get a blue screen error that says "Recovery. Your PC needs to be repaired" message. Please see my message above with a picture of the error.

If you have access to this other Mac Pro and can pull its stock card and temporarily install in your Mac Pro just for the install process then maybe that would work too (or alternatively, move your desired install drive temporarily to the other Mac Pro, install Windows on it there, and then move that drive back to your Mac Pro with the 7950.

I tried the second option, move the HDD for installing Windows 10 to the other Mac Pro, boot into the installer and install onto it (it actually works, the only difference between this Mac Pro and mine is that it has the stock GPU), and move the drive back. But as soon as I go to the boot menu and click on HDD labeled "Windows", black screen COMPLETELY.
Also about the monitor part, I'm using Dell monitors that only have VGA and DVI ports and my graphics card only has HDMI and Display Ports (I'm using Display Port to DVI adapters).

Where there's a will there's almost always a way.

This will will never give up!

 

[two-mac-jack]

I used this method to create my Windows 10 install DVD (for the Anniversary Edition).

Do you have any other PCIe cards installed, like for your SSD? If so, check out this thread. You may want to try installing rEFInd so you can force the system to boot Windows in Legacy mode.

I suppose you could re-flash your 7950 with code that's known to co-exist with Windows booting.

 

[bookemdano]

This will will never give up!

OK yeah your previous posts weren't clear that you had tried some of this so let me revise my advice now that you've provided additional detail.

Like two-mac-jack suggested above, remove any PCI cards too, except for the 7950. And put your Windows drive in Bay 1. And as I suggested before you might try wiping the drive of all existing partitions.

I thought when you said you chose the "Windows" option from the boot manager you were talking about the Legacy boot mode of the Windows 10 DVD. I think you need to focus on that, as I think the method giving you the "Your PC needs to be repaired" message is because the DVD is loading in EFI mode.

As for the black screen when you try to boot from the disk you previously successfully installed Windows 10 on, I think it would be worth trying a couple of things:

1. As soon as you choose "Windows" from the Boot Manager (or even before, and just have it highlighted and ready to hit Enter on, try unplugging the DP cable from your 7950. Give it a few minutes and then plug it back in. Maybe you'll still get the black screen, but also maybe you'd get an image. Worth a try in any case.

2. If you don't already have one, it's well worth having an HDMI->DVI adapter. HDMI and DVI are actually pin compatible with one another and DisplayPort is a really annoying "standard" fraught with weird compatibility issues and voodoo. I'm not saying an HDMI to DVI adapter would fix your problem but I do think it's absolutely worth trying (and worth having that adapter around anyway). They're cheap--couple of bucks on amazon or ebay.

To rule out some kind of issue with your cMP itself you could try transplanting the 7950 to the other Mac Pro and see if the same behavior results. Are you running the same firmware revision on both machines?

You could also try booting with both the stock video card and the 7950 installed (put the stock card in slot 1 and connect the monitor to it). Assuming it boots successfully, does it install drivers for the 7950? If so, try moving the cable over to the 7950 and see if it gives you an image. You could then try a reboot and just see what happens.

So much of troubleshooting is just throwing various combinations of things at the wall and seeing if anything sticks. Please update the thread when you've tried some of this stuff or if you ultimately get it solved.

 

[h9826790]

I have already mentioned in my post that when I go the boot menu and select the disc that simply says "Windows" (NOT the EFI option), the screen turns black and no input is working.
But when I boot off the other disc option that says EFI", the Windows logo at least appears!
But then this error shows up immediately after
And then follow the on screen instruction to finish the Windows 10 installation:

Shouldn’t stuck at black screen. I have the genuine Sapphire HD7950 Mac Edition card, a self flashed HIS R9 280, a non flashed R9 380, a non flashed 1080Ti, the stock Apple GT120 and HD4870. All work with this “holding C to boot method”.

How long that black screen last for? Did you give it enough time just in case it’s still loading?

If you can’t install Windows in legacy mode on a blank hard drive with this GPU. Then I can only assume you have a badly flashed GPU which cause the issue. (Especially black screen can point to a badly flashed card)

 

[mikeboss]

in my experience, the only GPU working flawless with Windows running in EFI mode is Apple's ATI Radeon HD 5770. with every other graphics card I tried I got crashes or weird behavior.

 

[HandsomePixel]

Just to keep track of what worked (or what didn't), here are ALL of the methods I've tried these past couple of days:
Burn the Windows 10 Anniversary ISO on 3 discs, one with the dd command, one with etcher, and today with this guide.

Boot off the DVDs (one after the other) by holding down the C key at Mac startup (Windows logo shows, "PC repair" error), holding down the option key and select the "EFI" labeled disc (Windows logo shows, "PC repair" error), holding down the option key and select the "Windows" labeled disc (just black screen, nothing else after 20 minutes).
And with all three, repeating these steps a second time, but this time while unplugging the Display Port cable and plugging it back in after 5 minutes when selecting/booting from the disc.

And the last suggestion, putting the installer discs in the other Mac Pro with the stock GPU and my dedicated HDD for Windows 10 to install on, successfully install it, then taking said HDD out and plugging it back in, hold ALT/OPTION at startup, choose HDD labeled "Windows"...and black screen for 20 minutes (I then just turn it off).

The problem can't be that Windows is taking too long to load the installer because it loads correctly in the other Mac Pro (again, only difference is it has stock GPU), and it even shows the logo, and was even able to load the error screen on my mac!

I'm stumped.

If you don't already have one, it's well worth having an HDMI->DVI adapter. HDMI and DVI are actually pin compatible with one another and DisplayPort is a really annoying "standard" fraught with weird compatibility issues and voodoo. I'm not saying an HDMI to DVI adapter would fix your problem but I do think it's absolutely worth trying (and worth having that adapter around anyway). They're cheap--couple of bucks on amazon or ebay.

Ehhh, I would really prefer all of my available free options.
Sorry, I'm cheap

 

[crjackson2134]

At this point I'd have to say it's the GPU flash-job. Seems like you've eliminated everything else.

Did you ever try the fully installed disk, but going to Settings > Startup Disk > Windows > Restart ?

I have NO reason to believe this would work, but just for the sake of methodical testing, I'd do it. At least you can add that to the list of didn't work.

 

[bookemdano]

Just to keep track of what worked (or what didn't), here are ALL of the methods I've tried these past couple of days:
Burn the Windows 10 Anniversary ISO on 3 discs, one with the dd command, one with etcher, and today with this guide.

Boot off the DVDs (one after the other) by holding down the C key at Mac startup (Windows logo shows, "PC repair" error), holding down the option key and select the "EFI" labeled disc (Windows logo shows, "PC repair" error), holding down the option key and select the "Windows" labeled disc (just black screen, nothing else after 20 minutes).
And with all three, repeating these steps a second time, but this time while unplugging the Display Port cable and plugging it back in after 5 minutes when selecting/booting from the disc.

And the last suggestion, putting the installer discs in the other Mac Pro with the stock GPU and my dedicated HDD for Windows 10 to install on, successfully install it, then taking said HDD out and plugging it back in, hold ALT/OPTION at startup, choose HDD labeled "Windows"...and black screen for 20 minutes (I then just turn it off).

The problem can't be that Windows is taking too long to load the installer because it loads correctly in the other Mac Pro (again, only difference is it has stock GPU), and it even shows the logo, and was even able to load the error screen on my mac!

I'm stumped.


Ehhh, I would really prefer all of my available free options.
Sorry, I'm cheap

Cheapness can sometimes be someone's downfall. If your problem is DisplayPort related then you can use different boot discs a thousand times and never get anywhere. If you're truly that cheap you could probably go down to your nearest Best Buy (or similar type place), buy one, and if it doesn't get you anywhere then return it. Like I said, such an adapter could be useful to have around anyway. My reasoning for this suggestion is perhaps due to the funky EFI on your card, the DP output is disabled under Windows. Or somehow under Windows the card is not sensing the DP output is connected and thus is not enabling that output. There are lots of possible reasons to try another output on the card.

I don't believe you tried my other suggestion of booting with the stock GPU in slot 1 and the 7950 installed above it (with the monitor connected to the stock GPU). Does Windows boot in that scenario? Do drivers load? Does the card show up in device manager as working properly? If so, can you move the video cable to the 7950 and get a picture?

And the other guy's suggestion of flashing a different EFI ROM onto your 7950 is a good one. There's one floating around this and netkas forum that most everyone here with a 7950 has used successfully. I'm sure you could find it (along with the flashing procedure) via some searches.

 

[HandsomePixel]

The thing is that I sold my stock GPU (the Radeon 5770) a while ago, although that is the exact GPU the other Mac Pro I've been using to successfully install Windows on has.
Do you think it would be possible to stick my Radeon 7950 into the other Mac (WITH it's default GPU) and flash it there on the windows install there?

 

[bookemdano]

Maybe others can answer more definitively. I remember using an actual PC to flash my 7950 when I had it. But that could have just been because I had one readily available (and did not yet have a boot camp partition on my cMP). I think the flash itself actually was done from a bootable DOS USB stick (maybe there's a way to do it from within Windows but I'm pretty sure I used a command-line version of ATIFLASH). I'm also not sure how/whether it works to flash the card if you have another video card installed (especially another ATI card).

 

[crjackson2134]

WinFlash can be used, but I alway trusted a DOS flasher more than others.

 

[h9826790]

The thing is that I sold my stock GPU (the Radeon 5770) a while ago, although that is the exact GPU the other Mac Pro I've been using to successfully install Windows on has.
Do you think it would be possible to stick my Radeon 7950 into the other Mac (WITH it's default GPU) and flash it there on the windows install there?

ATIWinFlash is fine.

But if just a badly flashed card. The other ROM on the 7950 should still work. Did you try that?

If you ate lucky enough. Then the seller didn’t touch that one. It won’t show boot screen. But by holding C to boot, the installer can use the generic VGA driver to activate the card.

Then you can install Windows, and use the same cMP to “rescue” the other ROM.

 

[HandsomePixel]

Somewhat great news! I in fact DO have the switch on my AMD Radeon 7950 GPU!
Which means it probably has the non-flashed portion of the GPU and probably means it can boot from the installer?
I will report back soon if it can install Windows.

 

[bookemdano]

Somewhat great news! I in fact DO have the switch on my AMD Radeon 7950 GPU!
Which means it probably has the non-flashed portion of the GPU and probably means it can boot from the installer?
I will report back soon if it can install Windows.

I was pretty sure all/most 7950s had the switch. It depends on whether the ebay seller flashed whatever onto both BIOS chips (flashed the card, flipped the switch and flashed it again). Absolutely worth a try though, which is why I suggested it in my first post

 

[HandsomePixel]

IT WORKED! YES!
Thank you all for your help!
Although I had to use the disc where I used the dd command to burn the Windows ISO onto on.
The other 2 still crashed for some reason, but my "custom" one worked very well!
Hopefully this thread helps someone else in the future as well.

I am typing from the Windows install as we speak

 

[MisterAndrew]

Has it been determined why the 7950's EFI rom has trouble booting Windows in EFI mode, but other GPUs (Apple branded & Nvidia) don't?