I don't have an oscilloscope, just a Fluke I think 84, and some other cheaper multimeters.
I did replace my first HDD today, and noticed a huge difference.
But before that;
I formatted the surged HDD two times, and kept getting the same errors after restoring the OS from a backup.
I don't care to check for bad sectors, that takes forever on a large HDD.
But now it seems to be running normally.
But there is still a problem with cold boot power on.
I still have to jump start it some times. So I'm putting on an extra button for jump starting so my wife can get it running also.
So I'm not sure if its (Like Vince said) a problem in the power supply or on the mother board. But when I short the green and ground and hit the power button it starts up every time
A RAM problem also crossed my mind, for the data error problems.
Because every time I would shut it down an error message would come up for about 1/10th of a second about memory???? But Microsoft considers the HDD as memory as well as RAM. And the message was way to fast to read, just a flash.
And when I put in a different HDD the message stopped appearing at shutdown.
And hopefully my analysis is correct and I and my system is stable again.