And just like how skyscrapers help make the most of scarce land, HBM stacks enable significant space savings on PCBs. 1GB of GDDR5 may take up 672mm², but 1GB of HBM would require just 35mm² of space, which translates into over 90 percent in space savings.
As GDDR5 struggles to keep up with growing memory bandwidth demands, more chips are required, which in turn require more space. Clearly, that isn't sustainable, and HBM helps reverse the burgeoning size of higher-end cards. The Radeon R9 Fury X's PCB is just slightly over 19cm long, 30 percent shorter than that of the Radeon R9 290X, the previous generation's flagship.
HBM will enable much more compact high-end cards, which will in turn allow powerful systems to be assembled in cases with far smaller space footprints.