At random my Monitor turns black. I have phoned dell and got a new U2713hm sent to me, but sadly this problem is still happening. I have replaced the monitor. I have replaced the power cord. I have replaced the DVI cable The only thing I have not replaced is my Display Pork to Dual Link DVi adapter or my Mac mini. I have ran diagnostics on my Mac Mini with no problems showing. I am tempted to take my mac to a local apple reseller and see what they say. Energy save is set to around 45 minutes for the monitor. Any suggestions?