Laptop Shuts Down After 20 Seconds of Running Normally

[ollyfff]

So i recently picked up a laptop that was having issues for very cheap, replaced the motherboard and put everything back together hoping it would work. What issue i now have after about a month period of it working fine is that it boots normally, and then the CPU fan speeds up and it shuts off about 10 seconds later. The laptop is a Dell Vostro P06E001.

So far i have tried:
-Carefully reassembling the computer, making sure nothing out of place was shorting something
-Cleaning up the terribly done thermal paste and reapplying a new coat
-Draining the MOBO of power and resetting the CMOS

Also, today as i turned the laptop on after about a week break from it, i smelt a burning plastic type of smell. Could overheating be an issue? I hadnt considered it since the computer turns off before anything could overheat.

 

[kajabla]

20 seconds is not too long for something to overheat. The hottest components, like the CPU, can reach maximum heat in seconds, and if their thermal solutions aren't working correctly (apparently your TC reapplication was not a success) can overheat to the point of shutdown very, very quickly.
I would say that overheating is almost definitely your issue.

 

[ollyfff]

20 seconds is not too long for something to overheat. The hottest components, like the CPU, can reach maximum heat in seconds, and if their thermal solutions aren't working correctly (apparently your TC reapplication was not a success) can overheat to the point of shutdown very, very quickly.
I would say that overheating is almost definitely your issue.

So what steps should i take next? Attempt to clear the CPU fan of dust and make sure its properly seated? Maybe even reapply some thermal paste?

 

[kajabla]

I thought you already redid the thermal paste.
I wouldn't expect a little dust or even a fairly shoddy TC job to have effects this dramatic. I think there's something bigger going on, but I don't know what.

 

[ollyfff]

Yea, i thought you were saying that my paste job wasnt proper, but ill attempt to take it apart again and find and issue with the CPU. Open to any other suggestions.