Only thing I've done so far is change the risers and resintall the video graphics driver. I've tried to dowgrade/use the latest driver but still didn't resolve the issue. I'll try to reconnect the cables again and see.
Any idea if there is windows log when the OS freezes?
Right-click or tap and hold the Start icon. Choose Event Viewer.
The Event Viewer appears.
On the left, choose Event Viewer, Custom Views, Administrative Events.
It may take a while, but eventually you see a list of notable events.