Which OSX Do i use on a Mac Pro 2009

[EirikStrand1996]

hi, I just bought a Mac Pro 2009 2.66 (i think) with 3 Gb ddr3 ram and the stock graphic card.
I know the graphic card is not working but thats ok since i have a 660Ti laying around i can use.
Now the problem is the Mac does not have a HHD or / SSD so i need to buy one, also okey, was planing on doing it anyway, same with more ram.
but am not sure how to download an old OSX because i need and older i think..? well am not sure about this part. so... can anybody tell me how to proceed from her

 

[adam9c1]

If you need to, you can buy OS X 10.7 Lion on a DVD
https://www.apple.com/shop/product/D6106Z/A/os-x-lion

Once you have that you will be able to update to OS X 10.11 El Capitan
https://support.apple.com/en-us/HT206886
https://itunes.apple.com/app/os-x-el-capitan/id1147835434?mt=12

 

[h9826790]

I don't think Lion can drive 660Ti. From memory, this GPU required 10.8 or later.

 

[DeltaMac]

Also, Apple never has sold Lion on a DVD. You purchase Lion from that linked page, and Apple sends you a redemption code that you use in the App Store to download the Lion installer.

 

[adam9c1]

Get a Mac version gt120.
Which was factory for your tower.

Then you can install whatever OS and then swap your card.

 

[Synchro3]

GTX 660 Ti needs at least OS X Mountain Lion 10.8.3. You will have no boot screen with a PC GTX 660 Ti.

If you would have an Apple graphics card or EFI-flashed card you could install OS X 10.6.8 from DVD (an run without graphics acceleration), and upgrade over the App store to OS X El Capitan. But you don't have an EFI Card, so no chance to install 10.6.8 from DVD.

- Ask a friend for an SSD with Mountain Lion, Mavericks or El Capitan already installed, install the SSD in the Mac Pro, do the Mac Pro firmware upgrade 4,1 -> 5,1*, and you are able to install the newest MacOS Sierra.

* I forgot: Mac Pro firmware upgrade only possible with an EFI graphics card.

- Upgrade RAM at least to 8 GB

 

[MIKX]

I use Mavericks 10.9.5. It seems the most stable for my requirements but I recently installed Yosemite on a spare drive as it loads my ASM 1042 USB 3.1 card natively.

 

[CapnDavey]

You could pick up a used snow leopard DVD off eBay and upgrade from there

 

[Synchro3]

You could pick up a used snow leopard DVD off eBay and upgrade from there

No, he can't install Snow Leopard with a normal PC GTX 660 Ti -> black screen

 

[chrfr]

You could pick up a used snow leopard DVD off eBay and upgrade from there

Don't need to buy a used one when Apple still sells it new, likely for less than it costs on eBay: https://www.apple.com/shop/product/MC573Z/A/mac-os-x-106-snow-leopard