Can the M1 MBP drive a 4K display at 60Hz when not in clamshell mode? I have an M1 MBP. I connect it to my external display (DELL S2721QS) using a HyperDrive Viper hub.
When my MBP is in clamshell mode, the external display works at 4K 60Hz resolution. When the MBP is open, the external display only works at 4K 30Hz.
My hub and HDMI cable are both capable of 60Hz, as shown by the fact that it works when in clamshell mode. Does anyone know if the M1 MBP is capable of driving a 4K display at 60Hz when the laptop is open?
Yes, this is officially possible. Your MBP supports full native resolution on the internal display in addition to a single display up to 6K at 60 Hz.
To quote Apple's technical specifications:

Video Support
Simultaneously supports full native resolution on the
built-in display in millions of colours and one external display with
up to 6K resolution at 60Hz

M1 MacBook Pro 13&quot; - Technical Specifications
Italics added for emphasis
As you can see, the specs specifically say: &quot;Simultaneously supports&quot;.