Display switches brightness or color temperature randomly

[IBM1620]

My display switches at random between 2 brightness or color temperature settings. This has happened since I recently bought a new Samsung monitor (LC22F390FHNXZA | Serial: 0PKGHTNHA00023D) so it is the likeliest candidate. OTOH my graphics card (ATI Radeon HD 3200 on motherboard) is pretty old. I would hate to go to the trouble of returning the monitor only to have the same problem. Is there any way to tell which is the culprit?

 

[popatim]

you can disconnect the monitor from the pc and then power on the monitor and go into its menu and see if the issue happens there. If so then it is definitely the monitor. Otherwise you may need to borrow one from a friend.