# Any reason why laptop --\> TV via miniDP --\> DP --\> HDMI shouldn't work? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [November 5, 2014, 1:59am UTC](https://boards.straightdope.com/t/any-reason-why-laptop-tv-via-minidp-dp-hdmi-shouldnt-work/703694 "2014-11-05T01:59:07Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [November 5, 2014, 1:59am UTC](https://boards.straightdope.com/t/any-reason-why-laptop-tv-via-minidp-dp-hdmi-shouldnt-work/703694/1 "2014-11-05T01:59:07Z")
The old laptop had a DisplayPort port. My TV has an HDMI port. I bought a DP --\> HDMI cable, which worked, and promptly got a new laptop. This new laptop has a mini DisplayPort port, so I bought a mini DisplayPort to DisplayPort adapter so that I can use the same cable that was working before. Now neither the laptop nor TV shows any indication of being plugged into anything else. It’s possible I got a broken adapter, or that I am doing something that shall not be done. I’ve poked around the Google a bit but may not be searching correctly. Thoughts? ---
**Author:** ![jacobsta811](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jacobsta811/32/2893_2.png) [@jacobsta811](https://boards.straightdope.com/u/jacobsta811)\ **Post date:** [November 5, 2014, 2:13am UTC](https://boards.straightdope.com/t/any-reason-why-laptop-tv-via-minidp-dp-hdmi-shouldnt-work/703694/2 "2014-11-05T02:13:56Z")
You are probably running into the difference between “active” and “passive” displayport to hdmi. Your old laptop was able to output an HDMI signal over the displayport connection - it just needed to be converted to the right cable type. Your new laptop either can’t output an HDMI signal or the double adapter is screwing up the detection of the fact that you are converting to HDMI. Basically, you probably need an _active_ mini-displayport to hdmi adapter - one that has electronics inside. If your laptop says it can output HDMI over displayport, maybe a passive mini-dp to HDMI will work. > **[Active vs Passive DisplayPort Adapter: Whats the Difference? Why does...](https://www.migee.com/2012/12/20/active-vs-passive-displayport-adapter-whats-the-difference-why-does-eyefinity-care/)** > > Recently the idea of having my third monitor back, inspired from my days with a dual output AGP working alongside a PCI video card, had me piqued. I am currently running a Radeon HD 5770, which lik… ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [November 6, 2014, 2:45am UTC](https://boards.straightdope.com/t/any-reason-why-laptop-tv-via-minidp-dp-hdmi-shouldnt-work/703694/3 "2014-11-06T02:45:11Z")
The port is dual mode only if labelled as. … HDMI/DVI Compatibility is achieved with DisplayPort Dual-mode ports, which are marked with the ++DP logo, using attached passive adapters. The passive adaptors should work together, as the mini-DP port has the same pins, and signals(electrical standards) on the pins, as the larger version… All mini to regular DP adaptors are passive, so any thing that works with regular DP should work with the mini-DP to regular adaptor. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [November 10, 2014, 3:02pm UTC](https://boards.straightdope.com/t/any-reason-why-laptop-tv-via-minidp-dp-hdmi-shouldnt-work/703694/4 "2014-11-10T15:02:22Z")
The port is labeled ++DP. I understand that should be OK? It’s a ThinkPad X240, if that matters.