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Romahaaa

macrumors newbie
Original poster
Feb 24, 2021
15
1
Hi guys,

I just bought LG UL600-W 4K monitor (checked reviews attentively to be sure it works well with MBP 2015 model) and found that it's almost unusable - the mouse movement is a bit delayed (slowed down). In other words the cursor doesn't moves instantly, there is ~100-200ms delay between the actual position and the position where it should be.

I connected it by HDMI (monitor supports 2.0, I assume the standard cable do also support 2.0).
I am using Bluetooth mouse, but even touchpad input have the same delay.
Moving cursor from external screen area to MBP screen cursor starts to move as normal without any issue.

Furthermore, in Display settings there is no resolution and frequency selection anymore as it was before with another monitors.
big sur external monitor resolution missing - Google Search 2021-02-25 15-12-33.png

In general, for 5 years of my MBP 2015 15" (Radeon M370X) usage I almost always had some issues with external monitors. Just another example - attaching Samsung FHD Smart TV input is slowed down as well. Before I had another LG Ultrawide FHD monitor which I could use ONLY when MBP lid was closed, otherwise the CPU started to work very hard.

I never used Thunderbolt 2 to HDMI or Display Port connection....but not likely that the issue.

Please, advice something...I googled for entire day already trying to figure out, what's the problem.

Thanks in advance.
 

Romahaaa

macrumors newbie
Original poster
Feb 24, 2021
15
1
The reason was pretty simple - by some. reason my Macbook Pro HDMI port doesn't support 4K (while according to specs it should to). I bought Mini Display Port to Display Port 1.4 cable, and everything works perfect on 60hz 4K resolution.
 
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