01-10-2019 09:22 AM
I got a t480 and a Ultra Docking Station at work and i have a really really weired problem and i am struggling to find a solution.
My t480 (u8550 Processor) starts throttling after sitting ~ 10-15 minutes in the dock without any logic reason. Some facts i have to get a more precise picture of the problem:
Outside the dock and connected to the USB-C Charger including with the Laptop everything is fine, even for hours of Work. No Problems there, everything is fine and i get decent Cinebench scores everytime.
As soon as i put the Laptop in the dock everything is fine for about 10 Minutes. Then the throttling kicks in and the Processor looses more and more Power until the clock stays around 800mhz.
It doesnt matter in which energy mode of windows I am (high power, optimized, energy save).
If i switch on/off intelligent cooling in the Thinkpad Vantage software the cpu goes up to 1,5 ghz for about 2 or 5 minutes and then starts throttling again.
Uninstalling Vantage has no effect. (Horrible Software by the way ... It starts slower than my whole development IDE including scanning the whole Project ...)
Everything (Software, Drivers, Bios, Dock Firmware) is updatet to the newest version available through Vantage (Did an update again just yesterday)
I installed Intel Extreme Tuning Utility to find out the cause.
Its not about thermals! Temps are just fine around 50 - 65 C. Thermal Throttling does never kick in.
Its also not because of the Nvidia Card - I dont use it and it is allways cool. Ive read that some people had Problems with thermal throttling of the cpu because the gpu runs hot - but thats not the case on my machine.
What i can see is, that as soon as the throttling Problems begin "Power Limit Throttling" is either allways on or is most of the time. The Package TDP is then allways around 5 - 8 watts. Outside the dock its about 22 - 30 watts on load.
I have a workmate who got the same setup. We have both the standard Windows 10 Pro Version that came with the machine. I suspected my Dock to be the problem, so we swapped the Docke yesterday. I got throttling with his dock but he had no problem with mine ... I also pulled the power plug from my dock to reset it (dont know if this is a thing, but this was one suggestions i found on the net) but that also didnt help.
If i put the running laptop out of the dock the processor starts acting normal after 1-2 minutes.
Some explaination to the attached screenshot:
The first 30 Minutes today everything was fine. Laptop was sitting in the dock, i was working and happy that it didnt throttle. I was updating thunderbold firmware yesterday and uninstalled Thinkpad Vantage and everything looked fine!
Then the throttling kicked in. The blue spikes show the power limit throttling kickin in every few seconds forcing the core clock down. Later its just allways on.
On the right side there is a spike in cpu clock for about 2 minutes, thats where i toggled the intelligent cooling in vantage (i installed it after throttling kicked in again to check if this "trick" still works.) but right after the clock comes down gradually again.
I just have not the slightest idea anymore what to do ... There are only two options left for me to investigate:
Trying a clear, non Lenovo Windows Installation - for this i need to wait for this or the next weekend as i have to work with this machine right now ...
Swapping the SSD with my workmate and check if the behaviour is dependand on the machine or the windows installation.
01-20-2019 11:29 PM - edited 01-22-2019 05:27 AM
I Did a clean Windows install and let Windows handle driver installation. Everything went perfectly fine and i installed no additional Lenovo Software after that. But unfortunately no luck - 10min after it went into the dock it started throttling again.
Seems like I have to assume some hardware defect ...
Edit: Tried a different Power-Suppyl, but also no luck.
Edit2: Got the opportunity to try one of the smaller docks (USB C Dock), but i ran into the exact same problem again. Besides that this Dock (or the connection on my thinkpad with just one USB C for this Dock) was not able to drive 2 1440p Displays ...