Get 4k 60hz

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naluhh
Posts: 3
Joined: Thu Sep 03, 2020 8:22 am

Thu Sep 03, 2020 8:28 am

Hey Guys,

I want to get the LattePanda 864s to ouput 4k 60hz on ubuntu. What are my options?
I know the hdmi interface doesn't support it, but I noticed I can use hdmi over usb port with a HUB. Can I get 4k@60 like this? Or do I need to buy a usb to display port, then display port to hdmi?

Thanks!

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ccs_hello
Posts: 623
Joined: Sat Oct 13, 2018 9:16 pm

Thu Sep 03, 2020 2:51 pm

LP Alpha's CPU/GPU can only support 4K (3840x2160) @ 60Hz from its DP port or eDP port, not from its HDMI port.
So in LPA case, the 4K @ 60 can be accessible from its USB-C port with
a proper dongle (e.g., USB-C to HDMI adapter) ,
thru a proper USB-C power injector + HDMI combo dongle,
or a proper 4K USB-C monitor that can supply power to LP Alpha as well.

Note that "proper" is very important. Correct part is critical.

P.S. LP Alpha's CPU s just a mobile CPU/GPU wil a rather small TDP rating thus 4K @ 60Hz spec is just "on paper". Actual performance may not be as expected.

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naluhh
Posts: 3
Joined: Thu Sep 03, 2020 8:22 am

Sun Sep 27, 2020 4:35 pm

"So in LPA case, the 4K @ 60 can be accessible from its USB-C port with
a proper dongle (e.g., USB-C to HDMI adapter) "

I tried several usb c to hdmi, and none of them can get me 4k60hz. Any idea why? However with a usb c dongle that output display port, I was able to do it

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ccs_hello
Posts: 623
Joined: Sat Oct 13, 2018 9:16 pm

Wed Oct 07, 2020 12:32 am

Use this one from Amazon
CHOETECH USB C to HDMI Cable (4K @60Hz), HDMI to Type C Cable 6FT (Thunderbolt 3 Compatible) with 2018 MacBook Pro/ Air/ iPad Pro, 2017 iMac, Dell XPS 13/15, Surface Book 2, Samsung Galaxy Note 9/S9

Please note I direct-plug that cable into LPA's USB-C port and the HDMI end to a 4K monitor (3940x2160 60Hz.)
Nothing added in the USB-C side (such as power injector, etc.)
What it means is I have to supply power from the DC 4-pin connector. <-- Actually I have o bump the supply
voltage to 15V due to a heavy bursty demand during Windows start-up process. (When I used 12V DC, Windows startup crashed half way.)
You'll have to be careful if using 15V, since that DC power bus might be dual-use in powering other external PC extension board, etc.
In another word, high quality DC input arrangement is needed when Intel GPU (HD615) is used in 4K mode. Naturally YMMV.
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ccs_hello
Posts: 623
Joined: Sat Oct 13, 2018 9:16 pm

Wed Oct 07, 2020 8:40 pm

Adding a bit more info:
When I used the standard 1920x1080 FHD resolution, I checked the peak power consumption during the entire booting process (until Windows is started and I logged in with a basic Windows desktop, no additional program running.)
The power consumption was 20W or so.
When I redid the test using 4K 3840x2160 @ 60 Hz, the peak power consumption was about 27W. Yes, that's 33% more.
This explans the 4pin DC-in power feed has to be carefully designed to avoid Windows crashing due to a very brief/intermittent power brown-out condition.

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