How can an external drive damage a motherboard?

Question

I have an Asus Vivobook S510 laptop that I used for 1.5 years. With the laptop on, I connected to the USB port a Toshiba external HD. As a result, the screen went blank.

I took it to the repair shop and they said that the motherboard wasn't functioning, and that I need to replace it (I'm struggling finding a new motherboard, but that's a different story).

Now I'm afraid to use external hard drives in general.  Why did this happen and is there a way to prevent this problem?

Answer 1

With the laptop on, I connected to the USB port a Toshiba external HD. As a result, the screen went blank.

There is any number of reasons connecting a malfunctioning USB device could have damaged your laptop's motherboard.

Now I'm afraid to use external hard drives in general; why did this happen and is there a way to prevent this problem?

There is any number of ways to design USB circuit on a motherboard. If it is not properly done, you can run into issues where a malfunctioning USB device, can cause any number of problems. There are USB devices specifically designed for this purpose. A fully functional USB device is nothing to worry about though.

Answer 2

The problem is bad motherboard design, and (without knowledge of your model) you could be being led down the garden path by the repair shop. You might want a second opinion from a shop that works at the chip level if its not a warranty repair. (If you are in a country with strong consumer protection laws you could be covered under fitness for purpose laws).

At a wild guess the drive may have gone faulty, drawn to much current and destroyes something, or static electricity (esd) may have been the cause.

What you are describing is very rare - most failures ive seen in this regard limit damage ti the USB port. There is no way to totally prevent the risk, but a quality powered hub ir docking station cpuld act as a sacrificial part/filter in some cases. Migrating to USB-C may also theoretically offer some protections.

It may be worth reading up (googling) "USB Killers" - usb sticks designed to kill systems - as the mechanism - ie a high voltage pulse eminating from a usb key - is very possibly analogous to what you experienced, and examples typically show ports blowing up, with better made devices limiting damage more.