Monitor connected to iMac causes it to crash the computer

I have a new iMac 27" (Retina 5k, 27inch, 2020 3.8 8 core I7/w 128gb Ram running Monterey 12.2.1

It keeps crashing when the second monitor (Acer KG281K) is in place

When it crashes the extended screen goes green and the main screen blank

it takes quite some time to recover by holding the power key

the logs are referring to a Kernel panic

I have read a few posts around the different forums and this seems quite common, with some people having success by

• changing cables
• changing resolution to below 60khz

I have reduced the refresh rate to 25khz and tried various resolutions and though that had resolved it, but then today it started crashing again. Currently on 3200x1800 on both monitors and Refresh rate of 30 Hertz - this is well below the cables support.

The cable I am using is from JB Hifi in Australia

https://www.jbhifi.com.au/products/alogic-ultra-usb-c-to-hdmi-cable-2m?queryID=00184fdea50ba9bce20306086a1eddcf&objectID=353809

ALOGIC Ultra USB-C to HDMI Cable (2m)

• Supports Ultra HD 4K (3840 x 2160) resolution @ 60Hz

I noticed it gets very hot at the back of the monitor ...the hdmi end - perhaps that is the issue...poor quality cable being sold as if it will do the job

What are peoples thoughts? Solutions?

Typing in the Mac model, I wonder if the cable needs to support 5k rather than 4k...

Thanks

Mark