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Author Topic: Dual 680's Mac Edition cards and Windows/Bootcamp  (Read 5053 times)

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« on: November 02, 2013, 06:32:17 AM »

I thought I was replicating a Mac Pro 5,1 dual 680 system described over in the MacRumors forum:

BUT I mistakenly purchased 680 Mac Edition cards. Which work fine in OS 10.9 but not in Windows8.1/Bootcamp. In Windows with one card all is OK but both cards in place will not boot.
Booting Windows with both cards with Option startup and selecting my Windows drive just freezes. If I set startup to Windows drive I get a minute or less disk drive activity and forever a white screen. (Like it doesn't know what to do.)

Might the bios flash described here (

make my off-the-shelf Mac Edition 680's more compatible with Windows??

Thanks! for any suggestions.
« Reply #1 on: November 03, 2013, 01:00:30 AM »

So basically there are issues with the GPUs BIOS Rom, you might say to reduce the issue to a single statement.

Idea: use a diffrent rom. Best: Use a ROM, that is already there. The GPUs EFI ROM
What I would try is:
- Backup the BOOTCAMP partition (Winclone, others might work)
- Delete the partition using Bootcamp utility
- make a new FAT formated partition using disk utility,
- install refind (fork of discontinued refit)
- reboot with a Win8.1 USB-stick/install disk attached (you can use earlier versions [7/8] and update them later on)
- you will get a new bootmenu where you should be able to select the installation Media in (U)EFI mode to boot from - if there is no Menu boot osx, login and restart. If you cant boot your installation media in uefi mode restore a Clover efi loader image (Google) to an GUID USB stick and boot the system from this. From this Menu you should be able to select uefi mode (worked for me on a MacBook Pro).
- reinstall windows, update, restore your files.

Good luck (if you'd like to test)

!!! You can also delete bootcamp at last if you prefere to keep it in case the others method won't work eighter.

You can uninstall refit/refind by deleting the EFI Folder on your root drive. Or instand of installier you can use a refind boot stick (you need to use and dd command to create it).

And always remember: i'm not responsible for anything.
Additionally to a hopefully working system you even will get a much faster booting system (stock EFI, vs. slow BIOS emulation)
After installation you won't need refind/clover anymore.

For reference you will find many EFI Windows on Mac guides out there on the net.

« Last Edit: November 03, 2013, 01:03:16 AM by RastaFabi » Logged
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« Reply #2 on: November 12, 2013, 06:24:23 AM »

The OP isn't going to come back apparently and post how he resolved so I will.

He posted at MR of this issue and I told him to try different output ports.

He spent 4 days doing Windows re-installs and driver re-installs, etc.

Finally he tried different ports.

And as you can tell from my smart-ass tone...THAT WAS THE PROBLEM.

Windows builds up config files or something that tell it to send outputs one way and the EFI hands it off another, that's the best explanation I can give.

In any case, if you ever have an Nvidia card that shows bootscreens going into Windows but goes black after that......TRY YOUR LOG IN. Listen for sounds that should go with log in. Unplug something, should make Windows sound effects.

If this happens computer booted. Now try different output ports. If you have 2 cards, believe it or not, it may have sent display to 2nd card. "Hot plug detect" will not always work.

Before asking a question, check your "Personal Settings" and be sure that you have "Brain Services" set to "On".
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