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Edinburgh, UK

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  • Registered: ‎06-10-2012
  • Location: Edinburgh, UK
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  • Message 1 of 5

t420s discrete graphics issue

2013-12-21, 6:13 AM

Hello guys,


My Thinkpad T420S (4171CTO) is freezing when I set BIOS to use only discrete graphics with OPTIMUS detection off.


Windows 8.1 Pro is booting up fine, but maybe within 20s after booting up the laptop freezes. Even if I will not log in and leave the system running for 20-30s it freezes as well. There is no BSOD, it's simply mouse and keyboard not responding and I have to hold the power button to shut down. 


I've installed Debian Wheezey 7.3 and it freezes as well.


When I set BIOS to use OPTIMUS, then Windows 8.1 Pro works fine and Debian Wheezy wors great as well, but it's only limited to Intel HD3000 integrated card. 


How can I diagnose my discrete graphics? 


Thank you


10 Posts



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  • Posts: 10
  • Registered: ‎01-21-2014
  • Location: toronto
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  • Message 2 of 5

Re: t420s discrete graphics issue

2014-01-27, 23:21 PM

I have this exact issue. I found a partial fix. You need to uninstall the lenovo monitor driver from device manager, but then you lose brightness control, so it's a driver issue on Lenovo's end.


Have you found a solution?




6 Posts


United States of America

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  • Posts: 6
  • Registered: ‎05-23-2016
  • Location: United States of America
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  • Message 3 of 5

Re: t420s discrete graphics issue

2016-05-26, 5:58 AM

You need to download Lenovo Thinpad LCD INF file in support.lenovo.com and follow Readme to install this can fix your issue. I had the same with T430, Win10 and resolved successfully.


1 Posts


United States of America

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  • Posts: 1
  • Registered: ‎04-09-2017
  • Location: United States of America
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  • Message 4 of 5

Re: t420s discrete graphics issue

2017-04-09, 13:49 PM

Issue persists also to Windows 10.

I downloaded the ThinkPad Monitor INF File for Windows 10 (32-bit, 64-bit) - Laptop version 5.07 at 13/07/2015 and installed it.

Nothing changed, problem still exists.
Discrete graphics mode still causes freeze.

Please provide the solution to fix this problem. Thanks alot.


33 Posts



30 Signins

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  • Posts: 33
  • Registered: ‎12-17-2016
  • Location: Sweden
  • Views: 293
  • Message 5 of 5

Re: t420s discrete graphics issue

2017-04-12, 19:03 PM

Have you tried to update your graphic and also the chipset drivers?
And if you have a update for BIOS or Intel Management Engine 11.6 Firmware try to update that as well.

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