M2 Mac Mini External Display capabilities

For the M2 Pro Mac mini, the HDMI port can support "up to 4K resolution at 240 Hz" (if you are using one monitor), or "up to 4K resolution at 144 Hz" (if you are using two monitors). There is no promise of support for refresh rates greater than 60 Hz over Thunderbolt or USB-C. I'm not sure what version of HDMI, or HDMI cables, you'd need to get the higher refresh rate.

For the M2 Mac mini, the limit appears to be 60 Hz.

Mac mini (2023) - Technical Specifications

Kyrolus wrote:

iiyama GB2470HSU-B1.

https://iiyama.com/gb_en/products/g-master-gb2470hsu-b1/

This is a 1920x1080 monitor with a 165 Hz refresh rate. According to the manufacturer, it has

• HDMI x1 (v1.4, max. 1920 x 1080 @ 144 Hz)
• DisplayPort x1 (v1.2, max. 1920 x 1080 @ 165 Hz)

If you download the user manual, page 37 (Appendix) suggests that it supports 1920x1080 at the following refresh rates:

• 60.000 Hz
• 119.880 Hz
• 144.000 Hz
• 165.000 Hz (DisplayPort only)

If you connected it via a USB-C (DisplayPort) to DisplayPort adapter cable, I'm not sure what rate you'd get – the Mac would be within specifications to support only 60 Hz, but might support one of the others.

With a M2 Pro Mac mini and a HDMI to HDMI connection, I think you'd get the 144 Hz as long as you did not try to connect three monitors to the M2 Pro Mac mini.

Mac's do not do well using the display manufactures cheap outsourced HDMI cable.

If switching to a short High Quality Premium Certified HDMI cable doesn't help,

then I would get and test that display on a 4K or better USB-C to DisplayPort cable.

for example > https://www.amazon.com/dp/B09NVV76FH/ref=sspa_dk_detail_5?

What brand and model is the monitor...?

In addition to the spec's that Servant of Cats posted, see > Connect a display to Mac mini - Apple Support