I have an Acer Aspire x1700 that I am trying to fix. I have replaced the 220w psu with a Seasonic 250w because this model is known to have bad power supplies (it wouldn't power on at all with the original psu). I also replaced the original thermal paste since I removed the heatsink/fan to clean it. When I got everything back in and plugged it in, no power. I read that the graphics card (Nvidia Geforce G100) can sometimes fail and cause the pc to not power on. I removed that and turned it on. This time it had power and booted normally to the Windows desktop. After about a minute the cpu fan became very loud, like a jet taking off, then it completly shut down. Could I have not applied the thermal paste properly and it was overheating?