[solved] 4k RX 580 Mojave @30Hz

[Rubinostu]

Hi guys, I'm desperate because I cannot find a solution to run my RX 580 at 60Hz.
I tried all solutions:
RedeonDeInit Yes/no
Intel Yes/No
Adding CFG_USE_HDMI20=true (after CFG_USE_FEDS) to AMD9500Controller info.plist
Changed iMac specs but no one of this solve me this problem.
I have a Samsung 4k monitor with HDMI cable 2.0
So many people told me that problem is cable (I bought DP-DP cable and I'll wainting for it) but I'm sure that HDMI 2.0 have to support 4k (other people send me screenshot where RX 580 works oob without any customizations or dsdt... nothing)

Installed Mojave with USB created by terminal, with clover added and kexts in "other" folder (lilu and whatevergreen included)

I don't know what I have to do and this problem going me crazy!
Please, help me!!! You're my last hope to solve this problem. Really thanks to people that can help me.

 

[P1LGRIM]

See https://support.apple.com/en-gb/HT206587

 

[Rubinostu]

See https://support.apple.com/en-gb/HT206587

In the page I have read:
"You can use 4K displays and Ultra HD TVs with these Mac computers:
[...]
iMac (27-inch, Late 2013) and later
[...]"

but this is my specs, have I to change it?

 

[Rubinostu]

Solved my problems... monitor wants DisplayPort-DisplayPort to have 60hz or DisplayPort - HDMI2 (on hd input number 2) to have 60hz.
Now I can use correctly my monitor: 4k at 60hz.
Thanks to every people that donate me their time replying this post.

 

[Michelinu]

It's very strange, maybe the monitor uses an old HDMI version

 

[samlll42]

Having the same problem. But can't solve it.

Both my DP ports on rx580 (Sapphire Pulse 8GB Ram) are connected to the gc-titan-ridge TB3 card to drive a LG 5k. So I have 2 HDMI ports left and trying to get 4k@60hz out of my Samsung U28D590 (which supports HDMI2). Tried different cable and even a HDMI to DP adapter.

Getting blank screen with HDMI-DP adapter.
Getting only 4k@30Hz with HDMI 2.0 cable (according to the monitor info).

Any suggestions?

I am contemplating getting a Vega 64 or another RX580 with 3 DP ports.... but I wish I could just fix my current config.

Thanks