The Most Comprehensive AMD Radeon Linux Graphics Comparison

Radeon HD 3650: The Radeon HD 3000 series is only a half-generation update from the Radeon HD 2000 series. The graphics processors are still part of the R600 family with only relatively minor changes. One change though was the introduction of the UVD+ engine, which again, is still crippled in open-source due to fears of compromising AMD's Digital Rights Management scheme. One of the other changes with the Radeon HD 3000 series was proper PowerPlay support for desktop graphics cards, but again, see the notes in the Radeon HD 2900XT section about open-source power management limitations. This graphics card was a Sapphire Radeon HD 3650 is running at 725MHz with the 512MB GDDR3 video memory at 1600MHz.

Radeon HD 3850: The ASUS Radeon HD 3850 is rated to run at 730MHz (above the reference spec of 668MHz) and 1900MHz (the reference spec here is 1650MHz) for the 256MHz GDDR3 video memory. With the similarities between the Radeon HD 2000 and HD 3000 series, once the HD 2000 series was up and running on the open-source stack, the Radeon HD 3000 series was up quickly thereafter (there were just some display-related change to work through, if my memory serves me).