After the Radeon 9800, the Radeon X800XT Mac Edition is back on the market and available.
To have the fastest Mac-dedicated AGP graphic card to be installed in a PMG5 AGP, it will cost you US$299 (VAT excluded). The card will sport 256MB GDDR3, and will come with a 3-years warranty.
Additional information: http://shop.ati.com/product.asp?sku=3170810
[translation by Linathael]
