Posted 17 July 2017 - 08:47 AM
First thing I would check or change with a known good one is the cable between the monitor and desktop.
Second thing I would check or change with a known good one is the monitor.
If no good results come from that than it may be leaky capacitors on the graphics card or on the monitor.
Another possibility is a failing power supply.
Linux Mint 18 Sarah Xfce (32bit) / Hp-pavilion-m7267c / Intel Pentium D Processor 820 Smithfield (2M Cache, 2.80 GHz, 800 MHz FSB, LGA 775 Socket) / Mobo: ASUS P5LP-LE, (Lithium-UL8E) / DDR2 Memory 4.0 GB, 800 MHz FSB / Graphics Card: ATI Radeon X600/X600 SE, (AMD/ATI) RV370 PCIE.
Windows 7 Professional (32bit) / Dell Optiplex 380 / Intel Core 2 Duo E7500 Wolfdale (3M Cache, 2.93 GHz, 1066 MHz FSB, LGA 775 Socket) / DDR3 Memory 3.0 GB, 1066 MHz FSB / Nvidia GeForce 8400GS (PCI Express) Graphics Card.