So... I have built maybe a couple dozen computers in 20 years and never had this happen. Thought it may help someone... Had a PC chugging along just fine (3 year old build, non-overclocked, high end components) that just refused to boot the other morning. Cracked the case, just about ZERO dust inside. Components like Fractal Tesla PSU, i5 3.4 GHz, ASUS VI Gene, matched RAM, SSD etc... surfing the web and scratching my head, I dug into the list of 'could be' items on Tom's. MOST all threads keep talking about dead motherboards, dead PSUs, dead RAM, and every time someone mentioned dead CPU the seasoned veterans would poo poo the idea as being so rare that it didn't make sense. Well... after a few hours and gutting a known good machine to swap parts... turns out my CPU just took a crap for no real good reason. Now, I ~thought~ that the machine would go through the post before really testing the CPU, but my symptoms were that the PC would attempt to start and then shut down a quarter second after hitting the power button. I just about lost my mind chasing potential shorts, or burned caps etc... I just never knew that a CPU check would happen IMMEDIATELY after pushing the button, or it would have saved me a LOT of time gutting my box and rearranging 6 other items chasing my tail. I am posting this in case there is some other poor soul out there that is surfing for answers.