Hot Hardware published a review on the AMD Details High Bandwidth Memory (HBM) DRAM Tech, Pushes Over 100GB/s Per Stack

A quote from the article:

High Bandwidth Memory is designed to address a number of limitations of current GDDR5 memory implementations. On many of today's graphics cards, a relatively large number of GDDR5 chips are necessary to offer sufficient capacity and bandwidth. The need to use a relatively large number of chips means a significant amount of PCB real estate is consumed by the memory and its associated voltage regulators. In addition, routing the traces required for a wide memory interface on a high-end graphics card significantly increases the complexity of the design. The power requirements for an off-chip interface are typically higher than an integrated solution as well...

 AMD Details High Bandwidth Memory (HBM) DRAM Tech, Pushes Over 100GB/s Per Stack @ HotHardware.com