If I had to guess - I think you got a bad stick or RAM. Especially since you mentioned you added some new RAM last Saturday. If you got a pair of RAM sticks - take one out and test your machine with 1 stick. if it's still bugging out - Swap out the RAM for the one you took out and try to boot with the other Stick. And check your MOBO manual - so you put it in channel 1 if you'll be the single channel in the proper slot.
When I had a stick of DDR Ram go out on a dell a few years ago - it caused all kinds of random shut downs - and not able to power up similar to what you're describing.