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walterross
Paper Tape
Posts: 2
Registered: ‎07-03-2011
Location: Colorado, USA
Views: 3,082
Message 1 of 4

T520 in ThinkPad Mini Dock does not show boot display DVI monitor

When my T520 is docked in a ThinkPad Mini Dock, I am unable to get the boot or bios displays to show on a DVI monitor attached to the Mini Dock.  During a normal boot with the ThinkPad docked and lid closed, I can "blindly" enter the Hard Drive password and the T520 will boot normally and Windows uses the DVI monitor just fine. 

 

Going into the BIOS setup (T520 is docked but need to use the laptop screen) the Boot Display Device option only shows choices for "ThinkPad LCD" or "Analog (VGA)".  There is no "Digital 1" or "Digital 2" choice as mentioned by the help text. 

 

My T520 is model 4239-CTO 

BIOS is level 1.21

ThinkPad Mini Dock Plus Series 3 is 4338-30U

 

Thanks in advance for any tips on making this work.

 

lead_org Microsoft MVP Contributor
Microsoft MVP Contributor
Posts: 21,009
Registered: ‎12-19-2008
Location: Australia, Melbourne
Views: 3,075
Message 2 of 4

Re: T520 in ThinkPad Mini Dock does not show boot display DVI monitor

do you have the optimus nvidia model? if you do, then you have to switch to discrete only in the bios menu, to be able to see the boot up screen in your dvi attached screen.

Regards,

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft
walterross
Paper Tape
Posts: 2
Registered: ‎07-03-2011
Location: Colorado, USA
Views: 3,050
Message 3 of 4

Re: T520 in ThinkPad Mini Dock does not show boot display DVI monitor

Thanks for the tip about turning off Optimus.  I found this combination of BIOS settings will enable the BIOS Boot Display Device option to show a choice for a the dock-attached DVI monitor:

 

Graphics Device -> Discrete Graphics

 

EnableOS Detection for NVIDIA Optimus -> Disable

 

However, I believe these settings will cause the Discrete Graphics Device to always be enabled ( ? ) Therefore battery life will be impacted when not docked and running on battery ( ? )  

 

It seems unfortunate there isn't a way to set Graphics Device to "Discrete" when docked and "Optimus" when undocked.

 

lead_org Microsoft MVP Contributor
Microsoft MVP Contributor
Posts: 21,009
Registered: ‎12-19-2008
Location: Australia, Melbourne
Views: 3,046
Message 4 of 4

Re: T520 in ThinkPad Mini Dock does not show boot display DVI monitor

that is true. But this is the only way right now to get the feature to work until the next bios release (hopefully Lenovo bios engineers will fix this issue with the next release).
Regards,

Jin Li

May this year, be the year of 'DO'!

I am a volunteer, and not a paid staff of Lenovo or Microsoft

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