4K through USB-C 2015 rMB?

jalm1

macrumors member
Original poster
Oct 25, 2008
38
2
I just got a 4K 27" HE Envy monitor and have a 2015 rMB. I would have assumed i would have been able to output at 3840 x 2160 over the USB-C monitor input which also charges the rMB. However, I can only get the output to 2560x1600. Maybe that was a bad assumption. Apple says the device can drive a 3840 4K using HDMI via a USB-C dongle. Why would it not also drive at 3840 via USB-C directly? Do i really need a HDMI dongle to connect to a USB-C monitor?
 

EugW

macrumors G3
Jun 18, 2017
9,038
6,419
Hmmm... 4K 60 Hz works with the LG UltraFine 4K monitor via USB-C directly with the 2015 MacBook. Perhaps there is a compatibility issue with the HP Envy?

https://support.apple.com/en-ca/HT206587

If you do decide to use a dongle or converter cable, I might suggest going for DisplayPort. Most USB-C HDMI dongles out there do NOT support 4K 60 Hz. They are mostly 4K 30 GHz, so if you are going with HDMI, you have to be very careful which one you choose.

EDIT:

It would appear to be a compatibility issue. A lot of people are reporting issues connecting to Macs. Check out the comments:

https://store.hp.com/us/en/pdp/hp-envy-27-27-inch-display
 
Last edited:

jalm1

macrumors member
Original poster
Oct 25, 2008
38
2
Maybe a compatibility issue, but that would be strange. There were a number of reviews on amazon indicating it worked. Most of the negative reviews seem to indicate a binary connection/no connection.

I can't do display port as that port is taken by my work machine (only output available). Does the Apple USB-C to HDMI adapter do 60Hz?
 

EugW

macrumors G3
Jun 18, 2017
9,038
6,419
I can't do display port as that port is taken by my work machine (only output available). Does the Apple USB-C to HDMI adapter do 60Hz?
I haven't tried it but apparently no. You would need a third party adapter.

Most of the combo ones with additional USB-A ports will be 30 GHz, because with the combo adapters you have a choice of 4K 60 Hz plus USB 2.0 or else 4K 30 Hz plus USB 3.0, so most manufacturers go with the latter.

I guess if you choose a HDMI-only adapter or cable, you are more likely to get 60 Hz, but check the specs.
 
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