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 d4650y (09/18/2006) / Intel Core 2 Duo Processor E6400 Conroe (2M Cache, 2.13 GHz, 1066 MHz FSB, LGA 775 Socket) / Motherboard: ASUS P5BW-LA (Basswood-UL8E) / DDR2 Memory 3.0GB, 800MHz FSB / Graphics Card: Nvidia GeForce 7300 LE [Nvidia G72] PCIE.
Linux Mint 18.2 Sonya Mate (64bit) / ASUS M2A-VM (06/15/2007) / AMD Athlon 64 X2 Processor 5200+ Brisbane (1M Cache, 2.70 GHz, 1000 MHz FSB, AM2 Socket) / Motherboard: ASUSTek M2A-VM / DDR2 Memory 4.0 GB, 800MHz FSB / Graphics Card: ATI Radeon X300 [AMD/ATI RV370] PCIE.