This is the current temperature reading, in degrees Celsius, from the onboard memory (DIMM) sensor on the IOM's own management-plane processor board, distinct from the card's overall enclosure temp field. Because a card's memory can run hotter than its surrounding sheet-metal-mounted temp sensor, this gives an admin visibility into a specific, often more failure-sensitive component. For example, a dimmTemp noticeably higher than the card's own temp reading, even while ambientTemp looks normal, would point to a memory-cooling issue specific to that component rather than the chassis environment.