...get no signal input error from my PC.? My vendor advise me to change to another power outlet. It Ok. But lately, I encounter more often of no Input signal. Don't tell to check the connection as this was properly checked.
Will this caused by power fluatuation of input voltage ?
Will install power conditioner help ?

Maybe your power source is iffy, or the battery is failing.Test the laptop with both replaced. If nothing changes the problem is inside so take it to the shop.
An offline ups is the best solution, a power conditioner the bare minimum.

The connection between the computer and the monitor is complaining.

But a UPS is always a good idea. Best and cheapest insurance you can buy.