ATI Radeon HD 4870

The ATI Radeon HD 4870 was a high-end graphics card marketed by Advanced Micro Devices (AMD) and released by Apple on March 3, 2009 as a build-to-order option for the 2009 1st-generation Mac Pro. It is based on a GPU chipset originally developed by ATI Technologies (which was acquired by AMD). It became available for pre-order separately on March 5 and shipped in May 2009, when Mac OS X 10.5.7 became available.

Description
The Radeon HD 4870 is based on ATI's high-end RV770 XT workstation graphics chip that was fabricated by TSMC on the 55 nm process. The GPU clock speed was 750 MHz, which could be boosted to 900 MHz, producing up to 1.2 teraflops. It contained 512 MB of GDDR5 video RAM. The card features one dual-link DVI port and a Mini DisplayPort. It took up the space of a double-wide PCIe 2.0 x16 slot, and required two auxiliary power cables.

Support
The Radeon HD 4870 required a minimum of Mac OS X 10.5.6 (Leopard), which was pre-installed on the 2009 Mac Pro. Mac OS X 10.5.7 added backward compatibility with the 2008 models, and Mac OS X 10.6 added support for all older 1st-generation Mac Pros. Some Mac Pros running Mac OS X 10.6.4 required a Snow Leopard Graphics Update for improved stability, which was incorporated into Mac OS X 10.6.5 and later. The card was supported through macOS 10.13.6 (High Sierra). However, it does not support Metal, and as a result will not work with macOS Mojave (10.14) or later.