I would have thought all would be installed with the os, so whichever card you put in, if there was a driver for it, it would find it. Certainly that's the case in my g4s with osx 10.4 and 10.5.

As of at least 10.7 (and I think 10.6), the OS includes drivers for all the video cards that were provided in Macs that are supported to run that version of the OS, including BTO options. Therefore in theory there's no need to download & install drivers. So ATI & Nvidia don't bother providing them.

This is why (for example) if a new Mac came out after the retail DVD version of the OS that runs on it went on sale, you couldn't use the retail disk to re-install the OS, you had to use the disk that came with the Mac. This was because the retail version wouldn't have the drivers for any of the hardware that came out afterwards and without them, you can't boot the mac far enough to install any 3rd party drivers anyway.

One of the advantages of digital distribution is the image you download (of 10.7 or 10.8) is always 'up to date' and has all the drivers for even the newest mac hardware bundled in and indeed they update the image file on everybody's macs through the app store when new hardware comes out.

Jon

So, the GPU arrived today. I installed it, and got nothing. The Mac start up chime happens, but then nothing further happens. Mac usually appears on network, but doesn’t now.

I’ve tried reseating RAM and HDs (again). Also unplugged and reconnected the card.

No diagnostic LEDs come on on the MB, so there is nothing being detected on the Mac.

Will try in the other X16 slot to see if that makes a change. Will also put old card back in and see what happens then.

Will have to contact the seller to see what advice he can offer as well. This is very frustrating.

Did you manage to run Hardware Tests and rule out the logic board?
Can you try another DVI/VGA cable to rule that out too?

So put old card back in to the Mac, and I get junk graphics on the screen just like before, which make me wonder if the GPU I was sent isn’t problematic.

Bah. Looks like they sent me the 32 bit version of the card, not the 64 bit one.

They all look the same, and no way to tell externally. The docket with say 2007 not 2008 (I know, should have read it first....). Have contacted the seller and hopefully they’ll take it back and ship me a proper one.

And such a quick turn around too - I wish they had taken a little more time reading which one they had put in the box.

Still, at least my Mac Pro isn’t as dead as I thought it was about half an hour ago.

I had to go out after I contacted the seller. He says he’d made a mistake, and has shipped me the correct card. He’s also included a reply paid label for me to return the other one to him. So we’ll see what happens tomorrow.

Replacement card arrived today. I fitted it, powered on and....

Nothing. Black screen. It chimes, fans spin up and that’s it. Nothing to indicate that it’s going through a normal start up procedure.

If I put my old card in, in starts up, and the display appears albeit with crap and junk on it.

Sorry, but sounds like the logic board to me

I am beginning to feel you are right. I wanted to try the GOU swap because that was the simplest and most obvious solution.

Since my last post I have done the following:

Tried booting from my MBP using targeted disk mode.

Tried booting with RAM in original configuration (with extra RAM taken out) and also with just the extra RAM. I bought a lump of RAM from Crucial.

Tried using the replacement GPU power cables supplied with the graphics card.

Tried accessing the Mac Pro from the MBP using an Ethernet cable.

Been resetting PRAM and the Power Controller.

All the above done with the old GPU and the replacement one, so each test done twice with the GPU swapped over each time. All yield the same results. Blank or patterned screen depending on which card is in.

I also skinned a knuckle swapping cards over.

I think I have exhausted everything I can do, and I now the new logic boards are not cheap, and I have to ask myself it it would be better to get a new machine or continue with the current one. Certainly, I'm at the limits of my abilities and anything further would require taking it somewhere to be mended.

At least I have backups, and I can access the HDs inside easily and drop them into caddies if needed.

Somewhat depressed here. I was hoping that machine would last me a lot longer than it did.

You need to test the video cards in a known good system before ruling them out. It is possible (although unlikely) that both cards are fried.
Do you have a friend with a similar machine.

If you are based in south london / croydon I can pop them in my machine if it would help.

Didge.