Dock Series 3 not putting monitor into power save

I have a T510 with a Mini Dock Series 3.

Everything works as expected ,except when using DisplayPort between the dock and my Dell monitor, the monitor will not go into power save. When connected directly using DisplayPort, the monitor goes into power save no problem, every time.

This problem happens for shutdown, hibernate and sleep. The only time power save works properly is standby. Wake on LAN and the other usual suspects all seem to be set properly.



Most often, after shutdown (etc,) the monitor displays "power save", goes blank for about 10 seconds, the comes back on, with "cable not connected" message (which means no power save).

Has anyone else experienced this?

Or, put another way, does anyone else have monitor power save working as expected with a Mini Dock Series 3?

 

I use a Dock Series 3 with a T410 and a DVI external monitor. It sleeps fine, so I wonder if it is specific to DisplayPort?

 

Good point. I'll test that and report back. It may be a quirk of the DP implementation on my Dell 2408.

I appreciate knowing that yours works...thanks.

 

realwarder: thanks, I can confirm using DVI solved my issues.

DVI seems to be using a color space (similar to an HDMI?) so there are slight color differences, but power save now works for sleep, hibernate and shutdown.

 

Glad to hear. If I ever get a DP monitor, I'll let you know if I have issues... but that may be a while as I've yet to have an LCD fail.

 

As part of the testing the DP connection further, I hooked an external HDD up to the dock. Once the TP is shutdown, the DP monitor goes into power save, and about 10 seconds later, the dock finally turns power off to the HDD. And then the monitor wakes.

It appears the dock power down sequence wakes the monitor up again. I reconfirmed that DP power saves properly when connected to the TP directly. So the culprit is the dock (and not the Dell monitor) for DP (only).

 

Lenovo has currently recognised an issue with the dock can't output to 2 DP port simultaneously, so this problem could be related.

Ken over at Lenovo seems to caught up to the problem, so you may want to get his notice and see whether this DP issues is a hardware problem that they could replicate on their engineering system at Lenovo.

Lenovo post on DP problem