I have a 2007 Mac Pro with a Radeon graphic card. It's red and plugs into the tower main frame. I recently purchased an LED cinema display and the mac sales rep said I needed to upgrade my graphics card. Does this new graphics card replace the Radeon one or do I just plug it into another slot?
Computers & Internet - ATI - RADEON HD 2400 PRO Graphic Card
Answers & Comments
Theoretically you can plug in 2 video cards at the same time. However, I believe both your old video card (likely a Radeon X1600XT) and the new video card (Radeon HD 4870?) both requires some external power plugs, as they require more power than the PCI Express slot can output.
There is probably not enough power plugs for both of these video cards at the same time. Usually a Mac Pro configured with multiple video cards uses a lower-end video card that can get power via the PCI Express slots only.
So I would suggest you to replace your current video card, and not use it alongside of the current card.
Also, what's interesting is that this video card is not "officially" supported on a 2007 Mac Pro. Although on the Apple forums everyone said it works just fine.
The new LED Cinema Display uses DisplayPort, which is a new standard that is not available on older video cards. There are no DVI to DisplayPort adapter (for connection of older video cards into the Cinema Display) that I know of. Although there are DisplayPort to DVI adapter to connect older DVI monitors to Apple's new video card.
It's a one-way backward compatibility thing, with no forward compatibility from older DVI/HDMI standards I think.
In this case it sounds like you will have to replace it, but why won't the GFX card you have cope? resolution or connectivity. The Radeon HD 2400 is quite a capable card.