Laptop cuts from external power when using too much energy

Question

I have Acer Aspire 7750G and I've had this problem for some time now. I had problems with my display, it was going white for some reason. When I got it back from a repair shop, they said it was a motherboard problem so they replaced it. For a month or two everything was fine, but then slowly problems started to arise. So now when I charge the laptop and it uses even a little bit more power then it does when it is idle, it disconnects the charger and the power button light with the light that indicates that the pc is on, start to blink together in equal intervals. If I disconnect the power supply and reconnect it again, it charges until it decides that it's using too much power again, it doesn't shut down the pc if I have battery in, just cuts from charging. And by a lot of power I mean I can't even watch a movie without it doing this again.

Answer 1

These are symptoms of a power supply that can't handle the load. It's unlikely that the replaced motherboard draws significantly more current than your old one; the repairs a few months ago are probably unrelated. The most likely cause is a failing power supply. It's fairly common for a defective charger to still deliver the specified voltage, so that it appears to work at first, as long as little power is consumed. When the computer starts using more power, the voltage drops too far and the PSU appears to be disconnected.

If you can, swap the charger for a different one with the same connector, same polarity and voltage (a small difference is often okay) and a sufficiently high maximum current specification (or you'll experience the same problems, but by design), to confirm your old charger is indeed broken and buy a new one if it is.