5870 for Boot Camp, GT120 for OSX

[Tesseract]

OK, potentially silly question... and I hate to be a help-leech, but I've searched far and wide and haven't found a solution.

Finally got my Sapphire 5870 Vapor-X hooked up to my 2009 MP... and been trying to get it set up so I don't have to pull the old GT120 GPU out of the PCIe slot every time I want to boot up in Windows Vista x64 on the 5870. The GT120 still boots up beautifully to OSX with the 5870 in, but I can't seem to get the 5870 as default on WinVista64. My guess is it has something to do with the EFI, as I get the gray "pre-apple" screen when I boot with the GT120, but not with the 5870. The 5870 only starts to send out a signal once the Windows loading screen shows up.

I'm trying to completely (or at least effectively) disable the GT120 in Boot Camp/Vista x64.
Is it even possible without a BIOS?
I've already tried disabling the GT120 "Display Adapter" under Device Manager. Am I missing something else that is glaringly obvious?

 

[rickvanr]

Can you not just start up windows with your monitor plugged into the 5870 and not the GT120 and then plug your monitor into the GT120 and not the 5870 when you're starting OS X?

 

[Tesseract]

Nope. Just a black screen. Vista outright refuses to use the 5870 as a display adapter unless the GT120 is gone - even if the 120 is just sitting in the PCIe with nothing attached.

 

[macz1]

I think it's a problem with Vista. Only Windows 7 can run multiple GPUs of different manufacturers at the same time. You can try to uninstall the Nvidia drivers and install the latest ones of ATI...

 

[jav6454]

I think it's a problem with Vista. Only Windows 7 can run multiple GPUs of different manufacturers at the same time. You can try to uninstall the Nvidia drivers and install the latest ones of ATI...

That'll create more conflicts. nVidia is very hurt that users do a combination of GPUs, so they rewrote their drivers to disable all nVidia GPUs if their is a GPU from the competition, in this case ATI.

 

[Tesseract]

I think it's a problem with Vista. Only Windows 7 can run multiple GPUs of different manufacturers at the same time. You can try to uninstall the Nvidia drivers and install the latest ones of ATI...

Hmmm... that sounds right about the Vista thing. I'll have to do a bit more research. And yes, I already uninstalled the Nvidia drivers completely. I did that before even plugging the 5870 in.

That'll create more conflicts. nVidia is very hurt that users do a combination of GPUs, so they rewrote their drivers to disable all nVidia GPUs if their is a GPU from the competition, in this case ATI.

The thing is - that would be GREAT if the nVidia GPU would disable itself. I was hoping for that exact thing, in fact. Unfortunately quite the opposite has happened.

 

[Eithanius]

I'm not sure of this is of help to you dear OP...

I have a MP 2009 with GT 120 and 8800GT.

Recently acquired Sapphire 5770 Vapor-X plugged in and removed GT 120 while leaving the 8800GT in there. Both works fine under Windows 7, running ATI Stream and nVidia CUDA side by side.

I've also tested my 5770 with GT 120 installed, both worked fine. I have a Dell 2407WFP with both cards plugged onto the same monitor to make sure Windows detect them even though I don't use extended desktop resolution. I don't have Vista installed so I'm not sure if that's the culprit as what other posters suggested, but I do believe in the ATI cards being finicky. This is because I do have one prior incident - when my ATI is plugged onto the MP but not onto the display, it would not detect the ATI card, so make sure your display is plugged to the ATI card and is used as a primary screen when you boot into Windows.

This happens when pairing the ATI with both the nVidia cards on separate instances, so it's not a GT 120 problem.