Monitor keeps locking back at 4K, 30Hz.

[Jorn_1]

Dear Sir/Madam,

I am using a 4K@60Hz monitor, using a DisplayPort 1.2 to Mini Displayport adapter. It can easily do 60 Hz, but everyday after a while it's suddenly locked @30Hz. The only fix for this I found so far is:
1. Turn off PC. 2. Take out the DP-cable. 3. Start computer 4. Put DP-cable back in after Windows started.
Then the cycle repeates. Can anyone help me with this?

My specs are:
!Monitor 1(4K): LG 27UD58-B
Monitor 2(1080p): Samsung s24a350h
GPU: Radeon R9 280 (AMD drivers 17.X and 18.X)
CPU: Intel i5 4690 (non-K)
RAM: 2x8 GB Kingston HyperX Fury
PCB: MSI B85-G43 GAMING
SSD: Kingston Savage 240 GB (; running windows and some more SSD & HDD)

Thank you in advance

 

[geofelt]

I might first suspect the DP cable or the minidp to dp adapter.
I suggest you first buy a good quality cable with mini-dp at one end and dp at the other.
Taking an adapter out of the loop could be the difference.

If no joy, Then I suspect that there is some issue with the graphics card.