Power Consumption and Polling

Power Consumption

Intel clearly wanted to certify Optane Memory in the worst case installation scenarios, which means power draw must be kept considerably lower than your typical M.2 NVMe SSD. While the 960 EVO 250GB SSD draws upwards of 6 Watts at full load, the 32GB Optane Memory part draws closer to 2.5 Watts when loaded. It is worth noting that Optane has a higher idle draw (~1.2W) than the Samsung part (0.7W), seen at the far left of the plot.

For those curious about thermal throttling, all tests in this article were performed with no airflow directed at the Optane Memory module. Even the enterprise workloads and RAID-0 testing were performed with no observable throttling at any point in those tests.

Polling

As we discussed in out P4800X review, to get the best speed out of Optane, you need to poll the device instead of waiting for an Interrupt ReQuest (IRQ) to service the response. It appears that the Optane memory driver is polling in order to achieve the lowest possible latencies:

The above was observed during a saturated sequential read from data that was contained within the Optane cache. Such a read on its own would never peg a CPU core at 100%. This was an extreme example that could only be reproduced by our special tools. In typical use, a sequential read would never be sustained for a long period of time, as Optane Memory would ensure the read was completed as quickly as possible. Overall power consumption of an Optane Memory enabled system should remain similar to that of one without, but I do recommend the polling-associated CPU usage be re-eveluated for those looking to buy an Optane Memory enabled laptop in the future.

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