But when the monitor is re-connected to the desktop integrated graphic card the flicker instantly appear again and it become worst (totally distorted) if connected to the additional PCI-E graphic card module. In addition the CPU usage also influence the intensity of the flickers. These indication confirmed there must be other causes to this problem.
In order to find out the root cause of the flicker I have diagnosed the following.
1. CPU heats up
2. BIOS Virus
3. Graphic card drivers
4. Motherboard Defect
Although the graphic card could be the most compelling sign of faulty but i could not tested it because there is only one desktop computer. So the additional Graphic card was removed and the monitor connected to the integrated graphic card of the motherboard. Then the troubleshoot was initiated with the CPU - during the test it shows that when opening applications especially heavy software like Anti-virus the flicker is starting to get more intense. The performance shows the CPU usage and heats starting to rise drastically up to 100%. This indicates the CPU heats could be the root cause. But still we are not sure until, after cleaning the heat-sink and add more thermal paste to the processor the problem still remains as it is.
Then move on to the BIOS virus - Not really sure if there is anything called BIOS "virus" but anyway I have run Kaspersky boot scan and updated the BIOS ROM software to the latest. The result still no sign of improvement. Consequently I've uninstalled the graphic cards driver from Windows and Re-install new one. Although I know this is quite illogical as the flicker happens right from the start but it was done just in case it could be related. But as expected this does not work at all.
Leaving nothing else to check, I look for the CMOS setup screen and found that the Date/Time has been reset and the hard-disk boot detected some weird characters instead of the Hard disk attached to the motherboard. By then i am quite convinced the motherboard is faulty, it could be components that is related to the graphic card although i am not quite sure what it is. This is because when using the additional graphic card the screen becomes totally distorted but using the integrated motherboard graphic still flicker (not distorted) influenced by the CPU usage
So I've got a new motherboard to replace it and re-used every single existing components that have i.e. Processor, RAMs, Graphic cards. The computer screen is now back to normal no more flicker even from when the PC is turned-on until Windows or running any application software.
After further diagnosed on the hardware itself - i've found that the capacitors of the graphic card and the graphic card slot on the motherboard is bursting out due to overheating. This is the cause of the flickering of the internal and external graphic card slot