02-27-2017 10:44 AM
I'm having a strange issue with my P50 (FHD, Xeon, M2000M) where after using external displays, the system will drain an extraordinary amount of power. I documented this previously with no resolution, but have additional details regarding the situation.
During regular idle, I usually have around 6-7W of power drain. However, after using external displays (which I use every day), the computer can no longer idle at 6-7W, but idles at 14-16W. I have ensured that the dGPU has been deactivated and that there are no runaway processes eating up network, CPU, graphics, or disk usage. The only way to return to 6-7W power usage is to restart the system.
Upon further investigation, when the high power usage issue occurs, the CPU can no longer enter C8 state (higher power savings) and instead can only C6 as the highest power saving state. Additionally, when the dGPU is active, the CPU cannot enter C8 state, so I assume that after unplugging my displays an issue is causing the system to remain unable to enter C8 state.
I would appreciate if Lenovo Staff could respond. I'm unsure if this is a firmware issue or something wrong with my system, but I've had this issue since last August and my warranty end date is approaching.