> Radeon cards have: Architecture ( TeraScale 2 ), Generation ( Northern I. ),
> gfx chip ( Barts ) and marketing name ( HD 6870 ). For compatibility is
> most important gfx chip and architecture. The other two are misleading.

The "HDxxx" etc. names are completely misleading, yes, but the "Islands" names are of technical use if you know how to interpret them, e.g.:
- Evergreen = RV8xx GPU
- Northern Islands = RV9xx GPU

Evergreen cards are:
- HD... 5xxx, 63xx, 6750, 6770, 73xx, 83xx
- R5... 21x, some 22x

Northern Islands cards are:
- HD... 64xx, 65xx, 66xx, 6790, 68xx, 69xx, 74xx, 75xx, 76xx, 84xx
- R5... some 22x, 23x, 31x

Southern Islands cards are:
- HD... 77xx, 78xx, 79xx, 85xx, 86xx, 87xx, 89xx
- R5... 24x, 33x, 34x, 4xx
- R7... 24x, 25x, 265, 34x, 35x, 37x, 43x, 450
- R9... 25x, 27x, 280, 37x
- (RX...) 52x, some 53x