My monitor keeps blacking out for 1 second, maybe less. It always comes back on. The monitor is about 5 years out. Power supply probably. Just looking for ideas.

Prob about to die on you. That shows a clear sign that's it's about to kick the bucket. My LCD monitor did the same thing then a couple weeks later it wouldn't turn on at all and it was only a year and a half old, lucky for me i had the exsteneded warrentee and got it replaced for free.

Could a monitor about to die surge in someway? Maybe fry out socket on the motherboard?

No your monitor would just die, it wouldn't cause a surge to your motherboard and short it, because it sounds like the tube bulb itself is about to go out, which is why it's flickering. I wouldn't be shocked I mean your monitor is 5 years old. I'd say go replace it with an LCD monitor. You will see a huge diff now of days and LCD monitors are cheap now.

I just bought a Dell 19 inch widescreen lcd monitor at Best Buy for 200 bucks that came with a 3 year warrentee and it's a great LCD monitor for the price.

a couple of things to try
keep in mind that in manufactureing world that that monitor has served it purpose
in the amount of time you have had it
the manuf only expects about 3 years of lif on most product

if you can get ahold of a loaner monitor see if you get the same problem there is also away to troubleshoot the mon
i believe that you right click on desktop
then properties then settings then then advanced then monitor
you will see the htz here
lower the htz and see if it still has a problem

have you tried the monitor on another pc to make sure it is not the pc/graphics card that is faulty?