I never called you a liar. I was suggesting that making statements in BOLD like MORE THAN 12 VOLTS, WILL BE FRIED, WILL BE USELESS are not constructive. I fend many comments from people who got back from the store with their shiny new DVM and immediately post "I JUST MEASURED MY POWER SUPPLY AND IT IS SUPPOSED TO BE 12 VOLTS AND IT IS 12.4312345 VOLTS! I AM AFRAID!!"
I refrain from asking them not to post voltages to 6 digits and comfort them that 12 1/2 volts is fine.
I agree with you that it is silly to buy cheap, buy twice. And that it is not wise to buy a cheap power supply. That may be why I have a HP 6281A supply on the desk next to me powering my latest little board.
But, that does not mean I was suggesting you were telling a falsehood when I noted that modern computer equipment has a wider tolerance for input voltage than you indicated. Due diligence and caution are justified. Crappy power supplies are the bane of us all. But can we please keep it to the level of appropriate caution and not try to entice uncertainty and doubt where not needed?
I bought a power brick a few years ago that provided 12V 2A and 5V 2A on a 4 pin molex plug. I use it when I am running a hard drive on the bench with a usb->sata dongle. I just checked and Amazon sells them for 15-20 USD. Something like that might be a better choice for running a hard drive than combining two separate supplies, especially since that is what it is designed for. There is nothing inherently wrong with using two supplies or using a regulator to drop 12V to 5V if you are handy and so inclined. I just found it more convenient to have a single block plugged in to run power the drive instead of having two and a mess of wires to convert the outputs.