M1 Macbook Pro, external display; low refresh rate on HDMI, low DPI on Display port

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M1 Macbook Pro, external display; low refresh rate on HDMI, low DPI on Display port

M1 Macbook Pro running Sequoia 15.6.1

Docked to Kensington SD5700T via thunderbolt 4 cable

Connected to LG Ultragear 45GS95QE via USB-C to HDMI/ Display Port cable

When I connect to the monitor via USB-C to HDMI cable, everything looks clear, dpi is high as monitor allows but refresh rate is capped at 60 Hz.

When I connect to the monitor via USB-C to Display Port cable, I can run the the monitor up to 240 Hz and enable variable refresh rate but dpi seems a lot lower, very evident in blurry icons on the dock.

I've attached screenshots of both display settings below, running at the same resolution but with different refresh rates.

HMDI to USB-C connected

Display port to USB-C connected

I've installed better display and played around with a few options to no avail. I've also tried bypassing the thunderbolt dock, connecting the USB-C end of the cables directly in to the Mac, with the same results.

I'm currently running on HDMI as, for my use, dpi is more important. Just wondering if there is a way I can push this monitor to it's limits on both fronts.

MacBook Pro 13″

Posted on Aug 29, 2025 12:43 PM

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Answer 1

Aug 31, 2025 09:18 PM in response to AceMacAir

LG – 45 Inch UltraGear™ OLED WQHD 1440P 240Hz 0.03ms G-Sync Compatible 800R Curved Gaming Monitor

That's a 45", 3440x1440 monitor with a refresh rate of 240 Hz and a pixel density of only 84 PPI (according to LG – I calculate a slightly lower figure). That's lower than the pixel density of a 24" 1920x1080 monitor (about 92 PPI) or a 27" 2560x1440 monitor (about 109 PPI)., so text and icons may be a bit coarser than on those monitors.

I would guess that the USB-C to DisplayPort adapter cable is using DisplayPort Stream Compression and that 3440 by 1440 pixels @ 240 Hz may be forcing it to do so much lossy compression that you are seeing visible effects. But this is just a guess, based in part on the report that things work @ 60 Hz.

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