Horizontal static lines on auxiliary monitor

• <<. Changing HDMI cables. >>

Changing to a different HDMI cable is a check against a broken HDMI cable. Now you know your HDMI cables are not broken.

However, you don't know whether your HDMI cables are high enough spec to actually support the display(s) you are using, or whether the computers you are connecting them to are capable of advanced HDMI support high enough to run those displays.

You have complained about "three different monitors" but have neglected to name the exact make and model of any of them.

You have whined about a Mac studio and an iMac, but different model-years have different HDMI capabilities. What model-years of which do you want to talk about?

You posted a lot of complaints without any supporting technical details, without which there is no way to consider what the underlying issue might be.

Your issue is very likely one of exceeding the capabilities of your various equipment.

please post the make&model of any display you would like to discuss, so readers can look up their capabilities.

please post the exact model and model year of any Macs you are connecting.

if you are using any additional adapters or Docks, please post their exact models as well.

Readers here are not Apple employees. They are other users like you, who volunteer their time to try to help people.

LG 32UN650 appears to be a 4K display with

DisplayPort and HDMI inputs

the Mac studio 2022 with M1 MAX processor can directly output a 4K HDMI signal at 4K at 30 Hz, maximum.

Higher requires HDMI 2.1, which is COMPLETELY different electrically from all previous versions of HDMI. HDMI 2.1 requires cables labeled "ULTRA" and possibly "48G" to support its completely revamped signaling method. The free cable they 'shipped in the box' is clearly inadequate for this purpose, but will likely work at lower resolutions.

USB Adapters claiming to support HDMI 2.1 should not be taken seriously. They will get 'burn your skin off' HOT in use, and are likely to burn out quickly. Apple specifically recommends AGAINST their use.

to successfully run that combination of computer and display, you will need a USB to DisplayPort adapter or adapter/cable capable of 4K at 60 or higher. Make certain it really can reach those specs, as many are hyped as capable, but in the fine print you discover they fall short. For these high speeds, cable length is limited to ONE meter maximum. Longer cables will likely cause error, and the Mac will shut off the display.

HP E273 display appear to be a 1920 by 1080 display

with DisplayPort input, only.

Use of its built-in USB-3 Hub requires a separate USB-3 cord connection, not available for display data.

if some of the above is just 'word salad', or you want to discuss this more, please post back and readers will be happy to provide more assistance..

Start by calling AppleCare.

AppleCare Contact Info