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Thunderbolt 4 and Backwards Compatibility

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eskimochaos

Member
Joined
Sep 26, 2005
Location
ALASKA
I have been having a hard time verifying if Thunderbolt 4 is totally backwards compatible - all the way to DisplayPort 1.2.

I have two Laptops, one with two TB4 ports and another with two TB3 ports. I am able to connect my external Dell U3011 monitor to a USB-C to HDMI/DP adapter and a generic USB-C expansion hub via HDMI to my monitor with the laptop that has TB3 ports The laptop with the TB4 ports will not connect to the U3011 at all.

I took the machine with TB4 ports to Best Buy to try out a newly purchased USB-C to DP cable. It worked on only 1 out of 3 monitors that I tried. What gives? Why would the cable/device only work on one modern display? I thought it was the fact that my U3011 is approaching 11 years old; however, it appears there is something else that I haven't figured out?

Any help would be appreciated. Posting here since the LapTop section is ded.
 

ssjwizard

Has slightly less legible writing than Thideras
Joined
Mar 12, 2002
What brand notebook and what system chipset that can make a BIG difference in compatibility.
 
OP
eskimochaos

eskimochaos

Member
Joined
Sep 26, 2005
Location
ALASKA
What brand notebook and what system chipset that can make a BIG difference in compatibility.
Lenovo Thinkpad P1 Gen 5 with a 12800H and RTX A3000.

When connected USB-C to DP to the monitor, when I hit detect monitor in Windows, the monitor wakes from sleep but does nothing else.

I am pulling my hair out....not much left.
 
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