Probably asked endlessly, but you know.

[darcy2711]

So whats the difference between an r9 280x, 285 and 280? What are the benchmark difference between them? 

[Nineshadow]

Performance : 280 < 285 < 280x

 

The 285 is newer though.It has more features.

[asker509]

the 280 and 280x both have 3gb of vram and a 384 bus. the 285 however has 2gb and a 256 gb bus the 285 has a newer architecture as well. it usually goes 280<285<280x 

you can look through benchmarks here http://www.tomshardware.com/reviews/amd-radeon-r9-285-tonga,3925.html

if your looking for a 280, 285 or 280x consider looking at the 290 because of the gtx 970 prices of 290s are plummeting to the $250 range