Difference between AMD R* ***X vs R* ***?

[muscle_man]

The X versions are basically just an upgraded version of the non-X card

But aren't they released before the none x versions?

[arvark]

It's more correct that the non X version are downgraded X versions. Anyway nVidia for example had the 980 Ti ready but released it when it was the right moment!

[-iSynthesis]

What is the difference between AMD R* ***X vs R* ***?

I am planing on building a mid range gaming PC, and was wondering which one would be more suitable for me.

Non-X chips are cut down versions, with X they are fully unlucked, similar to TI on Nvidia cards. For example the 280 is an old 7950 and the 280x the 7970; the 7950 was a 7970 with a few less cores, i believe you could bios hack it to get it to a 7970.