4k hdmi cable does not output > 1080p

[high_revs]

not sure why but my dell L521X laptop has two output connectors - hdmi and mini dp2. the old 27" 1080p is connect via hdmi and the 37" (capable of 3440x1440) is using a display port / mini dp2 cable. somehow, i can only output max 1080p to my 37" using the hdmi. But if I use my hdmi to dp2 adapter, i can get 3440x1440.

i also bought a 4k hdmi cable as my hdmi cables are rather old (says 1080p on the cable). but even then, i still only get 1080p via the hdmi port. but if i plug that hdmi cable to my dp2 adapter and to dp2 output, i get higher resolution.

doesn't make sense unless the hdmi output port is limited to 1080p only while the dp2 supports higher?

i bought the laptop in 2014.

[Robotron2k84]

The age of the laptop may indeed limit the resolution via HDCP if the version supported is too restrictive for anything higher.

DisplayPort is really a PCIe connection, so whatever adapter is embedded in the monitor handles the higher spec copy protection.

[high_revs]

i figured so.. my work laptop (t480s) shows a higher output than 1080p on hdmi, though i can't find the adjuster like hd tv where it can spread across my 34" screen vs. just like a box in the middle.

[sonofeugene]

Determine the make and model of your computer's video card and then Google it. Perhaps you can find some specs on it that will tell you what each output is capable of supporting. Probably a video card limitation.

[Robotron2k84]

i figured so.. my work laptop (t480s) shows a higher output than 1080p on hdmi, though i can't find the adjuster like hd tv where it can spread across my 34" screen vs. just like a box in the middle.

Being unable to span monitors is probably HDCP again. When any monitor or driver requests an encrypted handshake strict rules take effect as to maximum resolution and where encrypted content is output. Generally a video player that makes use of HDCP will only play on a single monitor and not spanning multiples. This is hardware and driver dependent, but if you could split the video over several devices that would open up hacking possibilities for copying the content, which is why it's disabled.

They do make HDCP defeat devices that strip out the copy protection, I'm not going to recommend that you do anything illegal, however.

Is the 37" a TV or a monitor? If it's a TV, that may explain things a bit as they run with HDCP active at all times, where a PC monitor will only engage it when a player requests it.

[high_revs]

Robotron,

I actually tested only one output - to the 37" monitor (monitor, not TV). Usually I use it for typical stuff like email, netflix/amazon prime, youtube in the 27" 1080p if I'm doing work. if no work, i use the 37" as my mail display (configured as such).

but with only the 37" connected to hdmi, it's still 1080p. i use the hdmi connector and use the mini dp2 adapter to the dp2 ouput, i get full 3440x1440.

on my t480s work laptop, i'm able to get higher than 1080p via hdmi. oh well.. maybe i'll just switch this to a desktop one day.