You have a Hewlett Packard model number M8000N media center personal computer with Microsoft Windows operating system installed, and your computer started shutting down for no apparent reason a few months ago. Now your personal computer system shuts down even before it can actually try to boot up the Microsoft Windows operating system. You have reformated the hard drive, replaced the power supply, and have even removed any extra random access memory module(s).
You have tried to perform a Microsoft Windows operating system restore as well and your computer still stuts down not expectedly. Do you have any suggestions as to what might be causing that problem you ask? You can check to make sure that all your computer system fans are spinning for example the power supply, case, and central processing unit fans.
If even one fan is failing it can cause your computer to potentially over heat and shut off. If all the computer fans continue to spin while your in the basic input output system or when the computer system is trying to boot that Microsoft Windows operating system, you can try removing any dust that has accumulated. Also, too much dust in and around your computer case fans can cause it to over heat and potentially shut off.
Does your computer system stay powered on for quite awhile when you are just accessing the basic input output system? Also, you will want to try booting that personal computer system into Microsoft Windows safe mode, last known good configuration, and or safe mode with networking support. You will want to remove as many physical devices as possible, for example compact disc, digital video disc, universal serial bus, smart digital card(s), etcetera. as possible in order to test to see if one of these physical devices is causing the computer to power off.
Another possibilty is that a hardware device is causing your problem. You may need to remove and install again those hardware devices one at a time until you find the culprit. Also, new hardware added to your computer recently might be causing your issue.
You can try dpdating your computer system basic input output system, which might help to solve your quagmire. If you have Microsoft Windows Vista or Vista x64 sixty four bit operating system there are basic input output system and firmware updates available from Hewlett Packard support website. A software and driver downloads web page has them available for download.
These instructions and tips were written for a Hewlett Packard desktop computer system with Microsoft Windows operating system. However, you could certainly use them for other computer brand and models. Also, you could use them as a basis point to troubleshoot other Microsoft Windows operating systems besides Vista.