A simplified approach to hotspot alleviation in microprocessors

Hotspots in microprocessors arise due to non-uniform utilization of the underlying integrated circuits during chip operation. Conventional liquid cooling using microchannels leads to undercooling of the hotspot areas and overcooling of the background area of the chip resulting in excessive temperature gradients across the chip which adversely affects the chip performance and reliability. This problem becomes even more acute in multi-core processors where most of the processing power is concentrated in specific regions of the chip called as cores. We present a one-dimensional, semi-empirical approach for quick design of a microchannel heat sink for targeted, energy efficient liquid cooling of hotspots in microprocessors. Our approach enables targeted manipulation of the local cooling capacity in the microchannel heat sink, which in turn minimizes the chip temperature gradient. The method is formulated to design a heat sink for an arbitrary chip power map and hence can be readily utilized for different chip architectures. It involves optimization of microchannel widths and flow rate distribution for various zones of the power map under the operational constraints of maximum pressure drop limit for the heat sink. Additionally, it ensures that the coolant flows uninterrupted through its entire travel length consisting of microchannels of varying widths. The resulting design estimate significantly reduces the effort involved in designing hotspot-targeted heat sinks.