|Run Memtest86 via a bootable CD (download ISO image and burn to CD) for a complete memory evaluation and let it run through ALL tests (I think there are 9 of them). It will continue cycling through all tests if you let it run. Any errors are cause to reject the memory. Run the test with all memory and again with one at a time.|
Make sure BIOS shows correct CPU speed. Try Default settings, but also try 'Load Optimal Settings' if you have that option.
Was this computer ever running properly? Is this a new build? Have you added or changed any hardware?
List your complete system specs. Include make and model number of system and/or components. List any changed components (like graphics card) that were not originally shipped with the system. List ALL specs on your power supply including make, model number, wattage, and amperage on any/all 12 Volt Rails.
You have to be a little bit crazy to keep you from going insane.