Understanding the Impact of Air and Microfluidics Cooling on Performance of 3D Stacked Memory Systems

Three-dimensional stacking has increased the memory bandwidth available to cores allowing sustainable performance improvement through technology generations. However, lower heat removal capability and higher DRAM density in such systems increases their temperature and requires larger number of rows to be refreshed at significantly higher rates. Higher operating temperature prohibits performance scaling by not only decreasing memory bandwidth availability but also reducing core frequency specially in the case where memory is stacked directly on top of the processor die (3D). Liquid cooling using microfluidics technology is a promising solution that keeps the temperature low increasing the operating range of 3D systems, thus allowing sustained performance improvement. This work attempts to understand the impact of temperature on performance and the advantages of using microfluidics technology for continued performance scaling. We show that conventional air cooling solutions limit 3D stacks to work only for memory-intensive applications running at low frequency, whereas microfluidics cooling technology allow them to push their envelope to not only compute intensive domains but also memory-intensive scenarios that can run at significantly higher operating frequencies.