Asus K555U taking extra current

[caspian]

Dear Members,
This laptop used to work with a 19v 3.4A adapter.
After 4 years of using it, now, the adapter's output voltage drops to 17v when windows loads up. Then the laptop suddenly turns off.
Today, I have connected a 19.8v 4.5A adapter to this laptop. Then the adapter's output voltage dropped to 19.4v but the laptop worked fine.
In addition, I noticed that the cpu power coils get warm to about 50'C but the mosfets are cool.
All the voltage rails on the mainboard are fine without any reduction except for the 19v rail. All the ICs and coils on the mainboard are cool except for the CPU coils. If I connect more components (such as hard drive or screen) to the laptop, the voltage drop is increased. The laptop charges the battery properly. The temperatures of CPU and GPU are fine under 50'C. the input mosfets are fine and not shorted.
In general, what may happen in a laptop so that the laptop has to take more input current from the adapter?

Regards

[piernov]

After 4 years of using it, now, the adapter's output voltage drops to 17v when windows loads up.

That's a bad AC adapter.

Today, I have connected a 19.8v 4.5A adapter to this laptop. Then the adapter's output voltage dropped to 19.4v but the laptop worked fine.

That's normal.

[Allgone]

From what I know the current increases depending on the work load, peripherals connected, if the battery is charging or not... Have you tried to plug your original charger with the battery disconnected? Maybe your battery is faulty, this can cause a raise in the consumption.

[caspian]

the extra current is taken by pure mainboard without battery, screen, and other peripherals connected.
However, if I connect battery or peripherals, the drawn current is increased.
HWInfo shows that CPU is taking between 1A to 8A of current. with a typical current of 4A.
The maximum current is taken when Windows is loading.
I do not know what takes this extra current.

[piernov]

After 4 years of using it, now, the adapter's output voltage drops to 17v when windows loads up.

That's a bad AC adapter.

Today, I have connected a 19.8v 4.5A adapter to this laptop. Then the adapter's output voltage dropped to 19.4v but the laptop worked fine.

That's normal.

[caspian]

That's a bad AC adapter.

That's normal.

OK, thank you
Your answer makes sense according to the symptoms that I observed.