"Lowly noobs" are just as equal as everyone else here
I gather benchmarks from several sources as well as performing my own (I see 20-30 new computers go in and out of my place each month). The benchmarks include 3DMark and PCMark, several games and CAD programs to test rendering capabilities.
The different versions are added then divided. For example a card can have 2 positions: 36 for the 512MB version and 31 for the 1GB version (these are completely random from my head so don't go check the list
). The two card positions are added so 36+31=67. Then divided by two since there are two versions (if there was another version, say 256MB then it would be divided by three). So 67/2=34 rounded off. So that card would place in position #34.
Hope that clears things up a bit more.