Haswell, Storage Drives and Power Management

I've come across this interesting article which discusses the effect of HIPM and DIPM on the processor package power consumption.

I've tested the findings of the article on my Dell E7440 with a Samsung EVO 1TB mSATA SSD. When I looked at the settings I found that both HIPM and DIPM were already enabled. I don't know whether this was done by Dell (I had cloned the factory Windows installation), by the installation of the Intel Rapid Storage driver or by the OS Optimization option of the Samsung SSD Magician.

With the computer on idle, wireless devices turned off and the display on minimum brightness the system power drain is about 3.65W of which the CPU package accounts for 0.8W.



If the Link power management is turned off in the Intel Rapid Storage console



then the system power consumption increases to about 5.2W (+ 1.55W) while the CPU package power went up to 2.1W (+1.3W).



This reveals that the main source of increased power consumption when the SATA link power management is disabled is the CPU package staying in higher power states. Only a small part of the increased power consumption is due either to the link staying active or additional power used by the SSD.

I also tested the link power management on my Sandy Bridge & Ivy Bridge notebooks with SSDs and, for those, there was no significant difference in power drain.

This issue is something to watch out for if the run time on battery is less than expected.

John

 

I have just put a Crucial M550 into my Dell E7440 alongside the Samsung EVO to see what it did to the power consumption. The CPU idle power went up to about 2.2W which suggested that the already enabled link power management wasn't working for this SSD.

So I disabled the link power management in the Intel Rapid Storage console, rebooted, re-enabled the link power management and rebooted again. The CPU idle power was then down to ~0.8W.

The lesson here seems to be that if cloning a Windows installation then it may be necessary to apply the above steps to make sure that the link power management is properly enabled.

John

 

interesting! ive manually enabled those two powersaving settings before in my windows installs but wasnt aware that it also contributed to saving power in the cpu package good stuff!