Monitor goes black in seconds. Help.

Monitor: AOC 22" LED monitor (a month old)
CPU: MAC Mini (late 2014 model - month old)
Connection: HDMI - DVI cable

My monitor suddenly turns black then display is back up in few seconds. The incident will continue to happen until, well, the monitor gets tired of the routine or till I decide to turn the whole thing off and resume in an hour or so... By the way this happens randomly.

the LED indicator is still lit which tells me that it is still running. It's just the display (or the signal) is lost.

To isolate the issue I have tried doing the ff:

• Connected the MAC mini to or LED TV (HDMI ready) for some time. Everything was fine.
• Connected the Monitor to a Windows PC via VGA - VGA cable. Fine as well.
• Bought a new HDMI - DVI connector (same brand with the other one) THE ISSUE STILL EXISTS.
• Set the Brightness, contrast to half. THE ISSUE STILL EXISTS.

can you identify where is the issue coming from? i'm betting on the cheap cables i bought (hope so..)

TIA