Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Do I add to existing graphics card or it replaces original Mac Pro 2008 card
Document: I ordered this graphics card for my 2006 Mac Pro. So far, it works great. I will update this review once I have had a chance to put it through it's paces.
The thing works like it should, but that said it's not a tremendous difference from the cards that shipped with the original mac pro. Does work right out of the box with the need for installing drivers. I have noticed some visual glitches from time to time. If you aren't concerned about budgeting, buy a higher end, newer, card.
After the original card died in my old Mac Pro 1,1 2.66ghz, this card works great! Showed up fast and was a piece of cake to install.
I heard this doesn't work too well with a mac pro 8 core system.But I have a Quad-Core 2.66 system. I upgraded from a 256mb Graphics Card and I gotta say that this was/is a "worth it" upgrade. I noticed a huge difference in all my games and editing software.I'm so buying a second one in order to "Sli" them both together. It's a must buy/upgrade for any gaming machine.Sender did a great job in packaging.
Ordered this one and had it installed within a few minutes of arrival. Cranked right up, and was a great replacement for a failing vid card on my Mac Pro early 2008 - just specify the model of yours on ordering. Good quality so far; haven't tried high intensity video games yet.
I needed a performance boost for Two 2006 Mac Pros (Xeon Dual-Cores with two Xeons in each box)  I own.The two nVidia 8800 GT's replaced the original nVidia 7300 GT cards (256MB) that came with the MacPros.The new cards provided exactly that-  a considerable performance boost, plus compatibility with the Windows Boot Camp environments I also run (as well as Mac OS X Lion and Snow Leopard.
i installed it on my mac pro 2.8 8 cores first generation . but there is no display comming out to my 2 monitors
With any of our older Mac Pro's, we need this video card.It is used by the Macs in our sound studio.
The graphic card works so smooth and quiet! It's all I need. I highly recommend this graphic card for MAC PRO!! !
Bought refurb model from Apple Core Tech. Arrived on promised date (no sitting in Oakland for six weeks). Pulled old card, installed new card, plugged in power cable (you need some itty bitty fingers), booted system, worked.What more can I say?
Answer: Hi Candace.  This should replace the original card - and should go in the same slot that the original one is removed from.  You will also need to attach a little jumper cable (provided in the upgrade kit) between the graphics card and a socket on the motherboard.  Whole installation should take under 1/2 hour including opening and closing the case.  So far, the card has been performing perfectly.  Good luck to you!Ken.