My Acer Aspire 7520 shuts down, loses power 5 - 25 seconds after powering on. It started when I was playing a video game and the laptop suddenly shut down. I thought it was overheating, so I let it cool down. About an hour later I turned it on and it boot normally, but 45 min. later the laptop shut down again. Next time I tried, it turned off 20, 5 minutes, then 30, 20 seconds later. In those 20 s after pressing the power button no errors or beeps occur, just the Acer logo screen. I even get past Acer logo sometimes or go to Bios password prompt if i press F2, just before laptop powers off. This all happened in the course of a few hours, laptop was working fine beforehand, no overheating (think so cause games lagged when laptop was overheating previously). If I turn it on again, just after it powered off, the laptop shuts down in 7 seconds, as opposed to 25 seconds if i leave it alone for a while. Also, according to task manager CPU and RAM usage is normal when shut down happens. Tried Cleaning out the fan and the heat sink (wasn't that much dust). Fan works. Applying new silver thermal grease to CPU and GPU after removing the old one. Powering on with only one RAM stick, then only the other (black screen when I take out both). Powering on without Wifi card. Powering on without the battery, only on AC power. Then only with the battery in. Powering on without Hard Drive. Powering on while putting pressure to the middle of the keyboard (read that this might pop the CMOS battery to it's slot if that's the problem). Pressing the power button for 1 min. There are a lot of people with Acer Aspire 7520 who have powering on and off in endless loop problem. Supposedly GPU reflow helps. I don't think my problem is the same, though because my laptop shuts down and doesn't restart. Also, my screen is working. This is the only computer I have. Any help or tips would be greatly appreciated.