AMD Radeon R9 280X OC 3GB Graphics Video Card Apple Mac Pro 1,1-5,1 *Monterey 4K | eBay
Refurbished: SAPPHIRE Radeon R9 280X 100363-4L 3GB 384-Bit GDDR5 PCI Express 3.0 CrossFireX Support Video Card Tri-X OC version - Certified Refurbished - Newegg.com
AMD Radeon R9 280X 3GB Graphics Card | eBay
Amazon.com: AMD Radeon R9 280X 3GB HDMI PCI Express Video Graphics Card for Apple Mac Pro, outperforms ATI Sapphire Radeon HD 2600, 4870, 5770, 7950, 9000, 9800 Gigabyte : Electronics