"upgrading" GPU on mac Pro 1,1

Recently, the video card (ATI Radeon 3870) on my Mac Pro 1,1 died. I have been searching for a replacement, and not having much luck. However, I've found 2 likely candidates and need some advice on which to pick.

The first is a Nvidia 8800GT 512MB, for $200
The second is an ATI Radeon 5770 1GB, for $266

Price to performance wise, the 5770 wins for sure. However, I'm not too sure it will work in my computer if I don't have Snow Leopard installed (before my computer became inoperable, I only had 10.5.8 installed on it). I have already purchased one card (gt 120) which didn't work as I only have a 1,1 mac pro and I am looking to avoid future mistakes. I know that I will have to upgrade to Snow Leopard to get the drivers for the ATI card, but will i be able to at least boot up my computer and install snow leopard on it if I buy the ATI, possibly in a limited resolution or color mode?

It really, really sucks that these are my only options for upgrading. Anecdotal evidence from Amazon customer reviews says that the 5770 will work on a 1,1 mac pro, but I have no idea if any of those users had snow leopard installed or not. Any help appreciated, thank you so much.

mac Pro 1,1
OSX 10.5.8
6GB Ram
quad-core 2.66Ghz
no video card

ashman70 said:

If these are Mac models, then go for the 5770, it will work in your Mac Pro 1,1 I had one in my Mac Pro 1,1 for almost a year, fantastic card, and well worth the money IMO.

Click to expand...

It is the Mac model, yes. Just curious, did you have Snow Leopard running when you installed it? That is literally my only concern about buying the 5770.

Ahhh, that's my problem - I'm running Leopard, the version right before snow leopard. I've read that snow leopard was the first version of OSX that had drivers for those cards, and that's why I'm concerned about not having it installed. I have no way of upgrading to snow leopard until I get a video card, so I don't want to buy a video card that requires me to upgrade to snow leopard first. Thanks for the recommendation on the 5770 though, if I hear that it'll work without snow leopard I'll definitely pick it up.

I don't see how I can, I have no video card at all right now so I can't even boot up my computer until I have one. If you can think of a way to do so, i'd love to hear it - the 5770 is sounding nice.

Well, after looking around it seems that the 5770 WILL allow you to boot to desktop, you just can't run any applications needing hardware acceleration because 10.5.8 won't have the drivers. But, it will allow you to upgrade to 10.6 with a disk. While I don't have a disk now, I can head to a nearby apple store and get one. I'll make sure to pick up one that is 10.6.4, thanks for the heads up, Cindori.