Thermal Issues in DRAM
Dynamic random access memory (DRAM) is a type of semiconductor memory that is typically used for the data or program code needed by a computer processor.
A completely new metric may be required to account for the multiplier impact of how thermal density gradually transforms minor concerns into severe problems at 14nm and below and in the most sophisticated packaging techniques. The heat produced by a few billion transistors has a much greater impact on reliability than a few overheated transistors.
This is especially true for AI/ML/DL designs, where high utilization increases heat dissipation, but thermal density affects every advanced node chip and package, utilized in smartphones, server chips, AR/VR, and many other high-performance devices. DRAM location and performance are now major design factors for each of them.
To take into account the fact that the charge is seeping out of those capacitors more quickly as the device gets hotter, you’ll start switching to a more frequent refresh cycle. Unfortunately, the process of replenishing that charge also uses a lot of electricity, which heats up the DRAM.
The more you have to refresh it as it gets hotter, but as it keeps getting hotter, the whole thing kind of breaks apart. The reason is that while all DRAMs are often placed next to one another, they are all at risk from high temperatures. Even with reliable server memory systems, the failure of a few DRAMs because of heat can cause the system as a whole to fail.
Why is this Issue not dominant in SRAM?
For SRAM, this isn’t as awful, but for DRAM it’s a significant concern since this refresh time is exponentially dependent on temperature because it’s a junction leakage. DRAM will suffer when combined with logic, especially if the logic is designed for high-performance computation. You must reload it more frequently when your refresh time decreases.
When temperatures approach the upper limit of the permitted operating range, a system can opt to increase the refresh rate of the DRAMs in some instances. The temperature affects how long a DRAM keeps its data, and greater temperatures may necessitate a higher refresh rate in order to prevent data loss. Higher refresh rates could have an influence on the system’s performance because they cause us to take some of the DRAM’s bandwidth away.
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