help please...3 year old np5720 failing

Sorry if this is the wrong place, but i'm really desperate right now. This all began when i came back from my summer vacation of 2 months long. Right after i got home i used the computer and it randomly shuts off or restart. I thought of various reasons and could come up with no definite conclusion. I ran multiple virus/spyware/malicious tests but all came up with nothing. The computer just shuts down or restart without warnings by just losing all the windows and then shuts down. If i have a program opened that cannot close which makes the computer unable to shut down, it just automatically powers off without going through any shutdown screen or procedure at all. The weird thing is it seems fine when its running on batteries but once plugged in it plunges into hell. I have even opened up the computer and dusted/blew out a WHOLE bunch of dust and it still seems to be hopeless. I also bought a new ac adapter from sager and that didn't change anything. I also reinstalled windows god knows how many times and the problem Just wont go away. Since i have windows reinstalled i dont think its a software problem anymore. While using the computer i also did some temperature check to see if its overheating and it hovers from low to high 40's. THank you for reading i know this is long but i'm just really frustrated right now. ANY help would be appreciated

 

goto>control panel>system>advanced tab>startup and recovery>turn off automatic restart

I also choose none for write debuggin information because with it i kept getting memory dumps when i turn off auto restart. but that might be the wrong thing to do. working so far though.

 

thank you for your reply...but the thing is it shuts off during safemode and when i was installing windows right after bios screen as well. Actually sometimes it even powers off in the bios screen....i do not know what is going on anymore.

 

I suggest reseating the RAM and video card next.

Before you do that, take out the battery and unplug the computer completely. Then hold down the power button for one minute to drain any excess electricity running around inside.

 

hey chaz thanks for the reply. I just found out that the smaller fan *5720 has a large fan and a small fan* wasn't running anymore. How would you fix this problem? Thanks.

 

you should make sure that the fans and vents are cleaned out (from dust) at all times.

use the Fan Toggle (Fn+F2) when the system is on to switch all fans to Max Speed or back to Auto speed.

thats how you would test the fans... as well as help prevent overheating.