Monitor only runs 70hz over HDMI1.4

HangTime · 1 Sep 2021 at 23:07

I have a 1440p 144hz monitor that runs at 144hz over Displayport from my PCs with different graphics cards in. All good.

However, I also plug it into my work laptop (Dell Latitude 7480) sometimes via HDMI, as it has no displayport connection. On the laptop, I cannot select above 70hz.

I've tried different HDMI cables with no joy. I know you need HDMI2.0 for 144hz but HDMI1.4 is supposed to do 75hz at 1440p, so why can I only choose 70hz?

MagicBoy · 2 Sep 2021 at 00:29

What's the GPU in the laptop?

HangTime · 2 Sep 2021 at 01:18

Intel HD 620

Evilpaul · 2 Sep 2021 at 08:28

Has Windows correctly detected your monitor, or is it using the "Generic Monitor" driver?

HangTime · 2 Sep 2021 at 11:49

Yes, I've also installed latest monitor driver and latest Intel graphics driver. I only get offered 59/60/70hz. I also tried to see if I could add a custom resolution like I can on my personal laptop (running HD 4400) but it's not an option in these drivers.

As it's a work machine I don't want to get too hacky and start running CRU or anything like that.

EsaT · 2 Sep 2021 at 15:46

With HDMI 2.1 we have this situation of some monitors advertised it for actually not supporting full bandwidth.
So who knows if same happened with 1.4.

Also different "blanking" might increase bandwidth need.
That 75Hz calcilation is for CVT-R2 reduced blanking, which is actually newer tvideo timing standard han HDMI 1.4:
https://en.wikipedia.org/wiki/HDMI#Refresh_frequency_limits_for_standard_video
https://en.wikipedia.org/wiki/Coordinated_Video_Timings