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Separate Graphics Card for Windows and OS X

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Biggy G.

Guest
Original poster
Jun 29, 2010
4
0
My job requires the Mac Pro as I do heavy video editing and rendering day in and day out and I much prefer OS X for my work. Just wanted to get that out of the way before someone posts "Just buy a PC then!".

I am wondering if it is possible to have a separate graphics card to use only in either Windows 7 or OS X. By that I mean, more specifically, use the Mac 4870 in OS X and use a Superclocked GTX 480 in Windows 7. Instead of buying a separate Windows 7 machine that I can't afford, I'd much rather have them both on one machine and perform the task via Bootcamp.

I've been thinking of ways on how to do this by going into the Windows Device Manager and disabling the 4870 and having the GTX 480 be the primary card. The only problem I'm thinking about is how I'll be able to use the same display with two different graphics cards when I switch over.


I'm wondering if anyone has any advice on if this can be done successfully and how to approach it. Any feedback is appreciated! :)
 
CaptainChunk

CaptainChunk

macrumors 68020
Apr 16, 2008
2,142
6
Phoenix, AZ
This topic has actually been beaten to death. You should search next time.

1. Virtually any PCI-E PC graphics card will work in Windows on a Mac Pro with no issues. However, during the initial POST (gray screen with Apple logo), you won't be able to see anything, including the boot loader unless the monitor is getting signal from the EFI graphics card (i.e. your 4870).

2. If you plan on having the 4870 and the GTX 480 in the same machine, you'll need to buy splitters for the PCI-E power cables, as there are only two headers on the logic board (and both cards need two auxiliary power connections). Also, keep in mind that the second PCI-E x16 slot isn't double-height, so installing a GTX 480 in there will block the slot (Slot 3) right below it.

3. If you have a monitor with two separate DVI inputs (my HP LP2475 is set up like this, among a lot of other third-party models), you can conceivably switch back and forth between video outputs just by switching the input on the monitor. If not, you'll have to manually switch the DVI cable from one card to another every time you switch from Mac OS to Windows, and vice-versa.


With all that in mind, there has been some speculation based on the drivers included with the new Mac Mini that Mac Pros will soon be able to support GTX 400 series graphics cards. So perhaps, a flashed GTX 480 that works in both Mac OS and Windows can be a future reality...
 
B

Biggy G.

Guest
Original poster
Jun 29, 2010
4
0
CaptainChunk said:
This topic has actually been beaten to death. You should search next time.

1. Virtually any PCI-E PC graphics card will work in Windows on a Mac Pro with no issues. However, during the initial POST (gray screen with Apple logo), you won't be able to see anything, including the boot loader unless the monitor is getting signal from the EFI graphics card (i.e. your 4870).

2. If you plan on having the 4870 and the GTX 480 in the same machine, you'll need to buy splitters for the PCI-E power cables, as there are only two headers on the logic board (and both cards need two auxiliary power connections). Also, keep in mind that the second PCI-E x16 slot isn't double-height, so installing a GTX 480 in there will block the slot (Slot 3) right below it.

3. If you have a monitor with two separate DVI inputs (my HP LP2475 is set up like this, among a lot of other third-party models), you can conceivably switch back and forth between video outputs just by switching the input on the monitor. If not, you'll have to manually switch the DVI cable from one card to another every time you switch from Mac OS to Windows, and vice-versa.


With all that in mind, there has been some speculation based on the drivers included with the new Mac Mini that Mac Pros will soon be able to support GTX 400 series graphics cards. So perhaps, a flashed GTX 480 that works in both Mac OS and Windows can be a future reality...
Click to expand...


Thanks for getting back to me on this. I've used the search function on this topic but I wasn't able to find much, maybe the posts were deep in a thread.

I have a few questions regarding your responses if you don't mind answering.

1. If I were to use a stock GT 120 instead which doesn't use either of the two power connections, would that be possible to pair with the GTX 480?

2. I'm looking into using a DVI splitter (which allows the user to change inputs) to allow me to easily switch between both cards when I boot into another OS as my monitor only has a single DVI connection. Would the use of one of these be a viable option?

3. How would I go about letting the OS know that I'm ONLY using the GT 120 and not the GTX 480 while booted into OS X? I believe I know how to do it in Windows 7 under the Device Manager.


I'm really just looking for a method to use until Apple officially releases support for the GTX 480.

Thank you!
 
CaptainChunk

CaptainChunk

macrumors 68020
Apr 16, 2008
2,142
6
Phoenix, AZ
To answer your questions, in order:

1. Yes. But I would probably move the GT 120 down to Slot 2 so the GTX 480 would be able to use the double-height slot (and thus you wouldn't be blocking Slot 3 for future upgrades).

2. Yes, that would work.

3. While you're booted into Mac OS X, any graphics card with a PC (BIOS) ROM on would simply be ignored (aside from reporting an unsupported expansion card in the slot in System Profiler), so that shouldn't be an issue. In Windows, you can simply just disable the driver for the GT 120 so it's not used.


And BTW, it's quite possible that the new Mac Pros will ship with either GTX 400 or Radeon 5000 series card options, so it might even be worth waiting for that to happen before a) you buy a GTX 480 that might not accept a future Apple EFI-64 ROM; or b) spend money on a DVI switch box (these can be expensive). But then again, this is all assuming that Apple (or a third party manufacturer like EVGA) will ship Apple-compatible GTX 480s specifically in the first place.
 
B

Biggy G.

Guest
Original poster
Jun 29, 2010
4
0
CaptainChunk said:
To answer your questions, in order:

1. Yes. But I would probably move the GT 120 down to Slot 2 so the GTX 480 would be able to use the double-height slot (and thus you wouldn't be blocking Slot 3 for future upgrades).

2. Yes, that would work.

3. While you're booted into Mac OS X, any graphics card with a PC (BIOS) ROM on would simply be ignored (aside from reporting an unsupported expansion card in the slot in System Profiler), so that shouldn't be an issue. In Windows, you can simply just disable the driver for the GT 120 so it's not used.
Click to expand...

Got it. Thanks again so much for the fast replies, answered all of my questions! :)

Hopefully others can benefit from this thread as well.
 
Cocoia

Cocoia

macrumors member
Jul 19, 2010
36
0
CaptainChunk said:
2. If you plan on having the 4870 and the GTX 480 in the same machine, you'll need to buy splitters for the PCI-E power cables, as there are only two headers on the logic board (and both cards need two auxiliary power connections). Also, keep in mind that the second PCI-E x16 slot isn't double-height, so installing a GTX 480 in there will block the slot (Slot 3) right below it.

reality...
Click to expand...

Not meaning to hijack the thread but its still related: what kind of splitter? 2 x 4-pin Molex (of the SuperDrive) to 8-pin? Are there other options?
 
CaptainChunk

CaptainChunk

macrumors 68020
Apr 16, 2008
2,142
6
Phoenix, AZ
No worries, bud. Glad I could help.


Cocoia said:
Not meaning to hijack the thread but its still related: what kind of splitter? 2 x 4-pin Molex (of the SuperDrive) to 8-pin? Are there other options?
Click to expand...

You can do it two different ways, depending on which Mac Pro you have. You can either leg off the Molex connectors used for the optical drives if you have a pre-2009 Mac Pro (the 2009 models are completely SATA and have no Molex power leads) or you would use a couple PCI-E power Y-adapters, like these ones. Basically, you would split the large ends (card end) with the adapters so you would have 4 total PCI-E power leads instead of just two.
 
Cocoia

Cocoia

macrumors member
Jul 19, 2010
36
0
CaptainChunk said:
No worries, bud. Glad I could help.




You can do it two different ways, depending on which Mac Pro you have. You can either leg off the Molex connectors used for the optical drives if you have a pre-2009 Mac Pro (the 2009 models are completely SATA and have no Molex power leads) or you would use a couple PCI-E power Y-adapters, like these ones. Basically, you would split the large ends (card end) with the adapters so you would have 4 total PCI-E power leads instead of just two.
Click to expand...

Thanks a ton. Last question, I promise: isn't splitting a 6-pin to two 6-pin or to an 8-pin dangerous? I expect it wasn't designed to provide for twice the amount of power. Pardon me if I'm being dense; I've searched around but couldn't find a definitive answer on this :)
 
CaptainChunk

CaptainChunk

macrumors 68020
Apr 16, 2008
2,142
6
Phoenix, AZ
Thanks a ton. Last question, I promise: isn't splitting a 6-pin to two 6-pin or to an 8-pin dangerous? I expect it wasn't designed to provide for twice the amount of power. Pardon me if I'm being dense; I've searched around but couldn't find a definitive answer on this
Click to expand...

You raise an interesting point, although the Mac Pro does have a 980W power supply and that shouldn't be a problem. However, I don't think Apple actually publishes the arrangement of its +12V rails (which is the single most important aspect of powering a video card), so it's probably best to see what others who have done this before might say.

I've been somewhat happy with my flashed 8800 GTS, which I use in both Mac OS X (work) and Windows (gaming).
 
M

mrbojanglesix

macrumors newbie
Nov 12, 2008
6
0
I have just undertaken this exact process, and everything worked great on the windows side. But in OSX.... here's what I did.

I have 2 drives in my mac pro 4,1 so I installed windows on the second. OSX on the first. After I had finished installing windows I went back to OSX to fool around and make sure everything worked, which it did. Then I installed the newest nvidia drivers, and plugged in my gtx 470 as is described above. Go into windows, everything works fine, card is fast, gt 120 still running the monitor.

So I try to boot back into OSX and notice the bootloader skips it, going right for the windows drive. So I option boot OSX and grey apple screen I just get a blue screen. So I pop in my 10.6 disk, and option boot the dvd, same story. Anyone have any suggestions? Apple won't really talk to me since its unsupported stuff. Help would be appreciated.





(side note: the 470 seems quiet, doesn't make much noise at all, not even while running at 20 gigaflops/sec with octane render (which seems like it would constitute "underload", seems hot in the back but that's what everyone says about it. Is there any way to monitor the fan, and make sure it is spinning up? And that I can't just hear the gt 120?).
 
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cakesson

macrumors newbie
Aug 30, 2010
6
0
I am in a similar boat. Have a mac pro 2008(3.1).
I run Nvidia 8800GT (mac). I recently added in an Palit's Nvidia gtx 460 (2gb ram) to use with octane render on the windows 7 64 bit side.

I booted in Windows and everything worked fine, I booted into osX and everything worked fine. I opted to install the latest software updates which included the latest snow leopard patch. When I tried going into OSX again, it would hang on the blue screen!!

Have tried rebooting. Cmd + s and doing fsck(?) and mount commands.
Last thing I did last night was popping in the snow leopard disc and opting to revert to time machine snap shot of before the update, but this morning it looked like the system restore had hung at 20% :mad:

Not sure what the best approach is at this point?
My issue seemed similar to yours so I wanted to see if you got it resolved and if anyone has any suggestions?

Thanks,
/Christian

P.S In retrospect I swear I read somewhere that the last snow leopard patch removed some nvidia graphics support (think I read it in some hackintosh board post). I am guessing this is why I am currently stuck on the blue screen.
 
M

mrbojanglesix

macrumors newbie
Nov 12, 2008
6
0
the fix

I'm still not sure what caused the issue, but I solved it by putting in the snow leopard disk which loaded (not sure what the issue was not loading the first time, but make sure you have your monitor plugged into the video card that OSX can use) and I ran the disk utility, then I ran the repair function on my boot disk, and after that it worked fine. I ended up reinstalling my gtx 470 and it caused the same problem again, and I repaired the disk again, and it worked fine again. I read on a forum somewhere that there is some sort of conflict between the nvidia 256 whql drivers, and the realtek audio drivers, so I rolled back the realtek audio drivers to the version from march and haven't had any issue since then. I didn't lose any data or anything. Hope this helps.
 
C

chych

macrumors member
Apr 28, 2010
50
0
My Mac Pro 1,1 would kernel panic on boot up with a PC Radeon 4870 in it (along with a Mac x1900xt) - problem was solved after I flashed the 4870. Just saying... perhaps the newer Mac Pros don't have this issue.
 
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