Today a Asus desktop came into our shop for repair works. It is a prebuilt desktop which is about 5-6 years-old. The interior is however relatively clean!
This PC does not have visual on the monitor and the CPU cooler is also acting weirdly. It spins for about half a minute then it starts to jerk randomly.So the CPU fan is definitely spoilt.
We used our own ram and we can see that the system is already booted up as the keyboard and mouse have response. So we removed the graphics card and connected the monitor to the motherboard. We managed to get visual on the monitor!
So this is the culprit for this PC. This Asus graphics card is spoilt and it does not allow visuals to appear on the monitor. The owner didn't want to install another graphics card to this PC as this is only for light usage. He went on to build a brand new one.