Computer shuts down on inserting disc

I have just fixed a computer with a similar problem. The owner installed a new DVD burner (a SATA drive) and every time he inserted a CD or DVD disc, the computer shutdown (mostly, because the front LED was still on and the CPU fan too, everything else just turned off [drives, PCI cards]). It happened in Windows, in Linux (Ubuntu) and even in the BIOS screen, so I discarded an OS problem. Also happened while booting if a CD or DVD was already inserted in the unit; as soon as the drive LED blinked, the computer crashed. After checking the obvious, I did three final tests:

1) try the DVD unit in another computer (it worked);
2) try the DVD unit with the power connector only, with the data cable disconnected (it shutdown);
3) try the DVD unit with the power connector from and external power supply, with the data cable connected (it worked).

By this point, it was obviously a power supply problem. I checked the power supply unit (PSU) and discovered it was pretty small (250 W). So I installed a more powerful one (350 W) and then it worked.

I checked with a wattmeter and it seems this DVD drive increased the power consumption by 25 watts when started to spin the disc. I really don't know if that is normal (taking 25W to start spinning the disc) or if this drive has some defect, but it seems the previous PSU could not provide that extra power and shutdown some of its output (but not all).

So, if you have this weird problem, maybe checking the power supply and testing with a bigger one may help.

Regards,

MV