Hi, I am checking on possible GPU upgrades for a technical application. I am wondering why there are 24Gb GDDR (12x SK Hynix H5GQ2H24AFA-R0C, each 2Gb) on a Radeon R9 280X with "3Gb". On the 6Gb version are 48Gb (12x 4Gb). What is all this excess memory used for? T.