From a forum posting, and the Ati site:


Purchased after august 31st, 2005...

ATI warrants to the original purchaser of the hardware product, that the product is free from defects in materials or workmanship under normal use and service for a period of one (1) year from the date of purchase at retail. If this product is a Workstation product such as ATI's FireGL or FireMV family of products, ATI warrants to the original purchaser of the hardware product, that the Workstation product is free from defects in materials or workmanship under normal use and service for a period of three (3) years from the date of purchase at retail. All cables and accessories provided with an ATI product are warranted to be free from defects in materials or workmanship under normal use and service for a period of for (90) ninety days from date of purchase at retail.
Purchased BEFORE august 31st, 2005

ATI Technologies Inc. warrants to the original purchaser of the hardware that the product is in good working condition, according to its specifications at the time of shipment, for a period of one to five years from the date of original purchase. The warranty term depends on the product. RADEON 7000 and newer products have a three year warranty. DV Wonder cards have a two year warranty. The Remote Wonder has a one year warranty. All other ATI products have a five year warranty.
Source: Extreme Overclocking Forums | ATI