Old sager m860tu inexplicably shuts down when playing games

[sam urias]

Hello everyone, this is actually my first time posting here, was in dire need to fix my problems. Anyways so what I have here is a older generation Sager M860tu laptop:

Specs:
Intel Core 2 Duo P9500 (2.53GHz/6MB L2/1066MHz FSB/25W TDP)
Windows Xp Profesional
15.4-inch WSXGA+ glossy display
Intel PM45 + ICH9M chipset
Transcend 2GB DDR3-1066 RAM (2 SODIMMS)
No Turbo Memory
Nvidia GeForce 9800M-GTS w/ 512MB GDDR3 video memory
320GB 7200RPM WD Scorpio Black
Optiarc DVD-RW AD-7560S
7-in-1 memory card reader
Intel Wireless Wi-Fi Link 5300 + Bluetooth

Some of the above specs are non stock. Anyways on to my problem, When ever i load up a game currently only tested on League of Legends, about 2 minutes in after the loading screen has done its stuff and either standing in the spawn pool or leaving base, My computer shuts down.... So I opened it up after this occurred about 3 or 4 times, i cleaned out all the dust, and took the heat sync off, and all the thermal paste had gone dry, so I took all that off and walked down to radio shack and bought some new thermal paste and applied that to the required areas. the Laptop now runs quite a bit cooler, but to no avail did that fix my problems. So yeh theres my problem, I will try out more games and see if my problem occurs through them as well, im guessing it will but maybe not.... Oh and one other thing the maybe this is my problem, I have no battery in the laptop, so its running straight off a the charger ( would get a battery but they are too damn expensive, about 120 dollars, and i am kinda broke at the moment ), and also that the problem does not occur when doing non game tasks...

 

[C12Friedman]

It sounds offhand as though your power brick (AC adapter) is beginning to fail, you can see if it feels hot while the computer is running - you shouldn't need to run games to check, wait about 3-5 minutes after turning the machine on and feel the brick. If it is hot (warm is okay) it likely needs replacing.

 

[sam urias]

So i after watching youtube videos for about 1-2 hours i check my power brick and it was hot but not to hot that you couldn't hold it continuously, Im not ruling it out as a possibility, but then i decided to run some temperature tests, Heres what i came up with:

Anyways i looked up average temps and this was noted to be quite low.... so that made me rule out overheating.... another thing that was weird and i found this out, the games can run perfectly fine when alt tabbed out of them, but then the instant I open the window my computer shuts down....

anyways I will relay this into the league help center see if they have something to say about it....

Thanks for your fast response and help