|Is this a desktop or tower computer, or a laptop computer? |
Are you overclocking this mboard /cpu?
"...sometimes it automatically shuts down while writing a dvd/cd or playing video or audio."
Probably - either your cpu (processor) is overheating, or the power supply is faulty.
Take a look in your mboard's bios Setup - usually you can find the current voltages and temperatures reported there somewhere.
The +3.3v, +5v, and +12v readings should be within 10% of their nominal values - if any of them are not, if this is a desktop, you must replace the power supply.
Even if those voltages are okay, the power supply may be faulty and cannot respond to the changes in load on it properly - e.g. DVD burning places an additional load on the computer.
What's the cpu temperature there, after the computer has been running a while, e.g. at least 15 minutes?
If the cpu is overheating, you will not be able to get the computer to boot for a while after the computer has shut down on it's own, until the cpu has cooled down some.
Overheating of the cpu is usually caused by it's fan and heatsink being filthy, or by the fan being faulty or having stopped spinning, or by you using overclocking settings in the bios that are heating up the cpu too much.
When the cpu has overheated, the bios of some mboards, depending on default settings you can't see or change, or changable settings you can see, will shut down the computer.
When a power supply is malfunctioning, the computer is a lot more likely to reboot than shut down the computer, unless the ps has overheated (e.g. it's fan is spinning too slowly or not spinning at all).
Rebooting can be caused by other things as well.
If this is a desktop computer.....
Failing power supplies are common and can cause your symptoms.
Check your PS.
See response 4 in this:
If it is failing, you can usually replace it with any decent standard sized standard ATX PS with the same capacity or greater.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo PS.
See response 3 in this: