Question Ram and monitor problem

[kristopheroAP]

Hello
Before 2 days ago I changed my pc case, and now when all my 4 ram sticks are in slots the pc monitor does not switching on. When I take off the last stick (slot 4) It is working. So the monitor turns on just with 3 ram sticks, when I plug in last (4) It does not. Why is it like that ?

 

[cin19]

So the monitor turns on just with 3 ram sticks, when I plug in last (4) It does not. Why is it like that ?

That RAM or the 4th memory slot has problem.