Yesterday I was given my brother's old laptop - core i7, 2.67GHz, 8GB RAM, 128GB SSD, Win7 64 bit. It's a Sony Vaio Z11. Approx 18 months old.
When running something computationally intensive, the fan starts up and after about 30 secs it just powers itself down with no warning. I guess it is overheating. There is nothing in the event logs to suggest what is causing it - the only thing I see is "the last system shutdown was unexpected" or something similar. This is a problem for me because I use a lot of number crunching apps, which pretty much makes it useless to me. I would like to know if there is anything I can do, other than the obvious things I've done already - open up and clean out dust, re-install the OS. According to my brother, this problem started about 6 months ago when it was already outside warranty. If it's just used for simple things - web browsing, word processing etc, the problem does not occur. Any ideas for what I can do to fix this ?
Update: I found that the laptop has 2 hardware settings for graphics: Speed and Stamina - the Speed setting seems to use an nvidia GEforce GT 330M, while the Stamina setting uses an Intel chipset. With the setting on Speed, I can hear the fan the whole time, and the system powers down after a short while (5-10 mins) even just doing basic tasks (browsing this site for example), but doesn't shut down if I just leave it switched on. In this mode it also sometimes just freezes the screen and I have to power off myself. However on Stamina setting it only powers down when doing number crunching and never freezes the screen.
Update2: I took the laptop to a repair centre and they say they "professionally cleaned out dust" and "removed heatsinks, cleaned old thermal paste, applied new thermal paste and reseated the heatsinks". They say they couldn't find anything wrong with it. The problem has improved in the sense that it now runs for about 3 mins instead of 30 secs before shutting down. I have installed Everest Home edition which shows that one core of the CPU (HTT unit #1) stays at 0% while the other 3 cores are at 100%. I thought this was a bit strange. I tried to post a screencapture of this, but it said "We're sorry, but as a spam prevention mechanism, new users aren't allowed to post images. Earn more than 10 reputation to post images." On a related note, I wonder why my question gets so many downvotes ?