[HELP] Sapphire Pulse RX580 : mouse&keyboard lags only in HDMI

Hi folks,

It took me nearly 6 months, but I finally managed to find something that does not work well with my i5-8600/Z370N-WiFi/RX580 hackintosh! ;)

Here is the thing: when I use a DisplayPort cable for the video, everything is fine. But when I try to use any HDMI port, the machine works but keyboard & mouse are frozen for about 1 second every 3 seconds... which makes it not quite usable.

I did some research on this forum, but could not fin anything. I have also tried a few tricks with no success, and here are a few remarks that could help with diagnostics:

• The Saphhire Pulse 580 (8GB) has 2 DP an 2 HDMI ports, all of them behaves the same: DP is OK, HDMI is not (I cannot test the DVI port)

• I tried using another HDMI cable and using HDMI with my main monitor (currently in DP) --> no luck

• I tried a DP->HDMI converter to plug the monitor on a DP port --> no luck

• The freeze seems to affect only USB inputs (mouse & keyboard): audio and video are not affected

• The problem appears both when the HDMI monitor is alone AND when both are connected

• The problem appears only in macOS, not in Windows nor in UEFI/Clover at boot

• During the freezes, the "kernel_task" uses one CPU core at 100%

• I chose my video card based on recommendations, and am using Lilu+WhateverGreen , no injection configured in Clover

I would like to use a HDMI connector for a second monitor that does not support DP, so I hope someone has an idea! The machine is on Mojave 10.14.3, I hope to try an earlier version soon if I can find a spare disk to test.

Thank you all very much !