Trouble with Sapphire HD 7850 mac edition graphics card

Question

So i've recently decided to updagre the graphics card from a HD 5870 to the HD 7850 mac edition.
It has a toggle switch for different firmware requirements of different OS's. It works great when I have it in "Mac OS X/Windows (non-UEFI compliant)" or "Windows (UEFI compliant)" as long as i'm booting into Mac OS X. With the former option i can hold down option to get a boot screen whereas with the latter the monitor becomes active as soon as you're logged in - as expected.
However as soon as i go to boot into windows by selecting my bootcamp drive from the boot menu (switch in position 1 on GPU)  it goes to a nice BSOD and i have to force restart my computer. Does anybody understand why this card won;t allow me to boot into windows like my HD 5870 did in this manner?
Secondly, i figured I would try to bypass the boot screen by throwing the GPU switch to position 2 ("Windows (UEFI compliant)") and then go into system preferences and select the windows volume to startup in. However ever since i installed windows i haven't been able to boot in this manner...when it restarts i get an error saying that there is "no bootable device" which makes no f****** sense because i can boot into my windows drive just fine by selecting it from the boot menu.
I feel like since i had to install windows by bypassing bootcamp assistant (directly booting from usb and installing to a clean separate internal SSD) that I might have screwd up the association between the startup disk selector and the target disk...i'm so exhausted of dealing with windows and my mac with RAID drives...so many problems, so complicated.
Any help with the graphics card stuff would be much appreciated.

Answer 1

Dear Paul S, John B here. I have a 2008 Mac Pro, single Quad Core-not state of the art  at all. I bought my sapphire radeon HD 7950 to replace an nVidia 8800, so that I could play Bio shock infinite on Steam. Yes, I installed it myself, it's a piece of cake.  I had no issues after installing. Some have...might have been that gpu switch on the side was defective, but not for me. to the right for mac, left for PC, as far as I know.  As for the hype, can't say.  It does the job quite well.  I now have a Mac that can use Display Port and HDMI for output rather than DVI (very handy for buying monitors- you can use a small LCD tv as one). I guess it was worth the price, to me it was, anyway.  I learned my lesson on older graphics cards: when they go, try to not have a fit, and see if you can replace them with something a bit better, and don't take your Mac in to your local Fruit PC store, cuz they don't have a clue about such things, and the Fruit PC company's policy is to replace like with like-period.  You can ask them to, but they won't put a better video card into your Mac Pro, even though you are willing to pay the difference to upgrade. Also, you are on their turf, so you will be paying their prices for that old video card. $360 for an 8800GT mac version? I don't think so, at least not again ! Freak out with Bootcamp? I don't think so.  I've never used it with bootcamp, but I did mention the switch, so I think you're covered there.  Maybe you'd have to download and install Windows drivers for that card but that's be about it.  You might try MacVidCards.com
but that's a crapshoot, as PC cards flashed to work with Mac may be.
just my 2 cents
JB