Will 3rd party graphics card for MacPro1.1?

Upgrade OS X to Snow Leopard and replace the GPU with Apple's ATI 5770.

Upgrading to Snow Leopard

You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.

After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store. Access to the App Store enables you to download Mountain Lion if your computer meets the requirements.

Snow Leopard General Requirements

1. Mac computer with an Intel processor

2. 1GB of memory

3. 5GB of available disk space

4. DVD drive for installation

5. Some features require a compatible Internet service provider;

fees may apply.

6. Some features require Apple’s iCloud services; fees and

terms apply.

Upgrading to Lion

If your computer does not meet the requirements to install Mountain Lion, it may still meet the requirements to install Lion.

You can purchase Lion by contacting Customer Service: Contacting Apple for support and service - this includes international calling numbers. The cost is $19.99 (as it was before) plus tax. It's a download. You will get an email containing a redemption code that you then use at the Mac App Store to download Lion. Save a copy of that installer to your Downloads folder because the installer deletes itself at the end of the installation.

Lion System Requirements

1. Mac computer with an Intel Core 2 Duo, Core i3, Core i5, Core i7,

or Xeon processor

2. 2GB of memory

3. OS X v10.6.6 or later (v10.6.8 recommended)

4. 7GB of available space

5. Some features require an Apple ID; terms apply.

Graphics cards without Apple firmware will generally not show a picture under Mac OS X.

The Apple-firmware 5770 (about US$250) works in every model Mac Pro, and drivers are available in 10.6.5 and later.

If there are drivers in the OS X version installed, then the non-Apple GPUs only fail to show an image during bootup. Once the system finishes booting the GPUs will display properly. They will also show the bootup screens if you use them in VGA mode rather than DVI mode.

I do agree, however, with the 5770 recommendation which was my recommendation as well. Given that the OP's MP is first generation there is really little point in using any GPU beyond the 5770 because whatever advanced features the GPU may have the computer's PCIe 1.0.x slots can't implement them. In fact the 4870 GPU would be just as good as the 5770 if one can find a used Apple version of the card. I've used both in a first gen MP and the ran just about the same.

I put the 5770 into mine only months ago, when I upgraded to Lion in March and feel I have a solid system to wait out the "1.0" blues of any new OS (10.9) or new hardware (6,1) both of which take time and time for everything to fit together (remember 10.3? 10.4? and on every other release). And the months for drivers and 3rd party too.

Consider it a "thank you for 7 yrs of faithful service" and to provide one before your 7300GT does blow a capacitor. That is actually older than 7 yrs graphic card design.

Look on MacVidCards ebay he has 1GB flashed 7300 too.

Here's my take. Your model has PCIe 1.0 slots. It cannot even take full advantage of the 5770 GPU let alone anything else. That means you waste your time and money on anything beyond the 5770. You don't wish to give up the boot screen, because without it you cannot use any form of OPTION booting or COMMAND keyboard entries unless you run the cards in VGA mode.

I would not recommend using any GPU other than the ATI 5770 Mac Edition. This will provide the best video performance you can get out of your hardware.