OK, been a long time since I addressed this issue, but happily the problem was solved.
My X has a good Radeon card in it (6870) but apparently there have been a lot of fan issues with it, and a dying fan motor appearded to be my issue.
I started timing the display screen blankings. They went like this 1st time: 7minutes, 53 second; 2nd 5 : 12, 3rd 3:47, 4th 1:45 etc etc
Each time the Amiga "died" earlier, so I started to suspect heat. Sure enough the fan on the Radeon card was the culprit...it turned but with a lot of resistance and it turned slowly...so as I rebooted the residual heat appeared to shorten it's "lifespan".
Bought a close replacement fan on eBay, it runs at .43 amp instead of .50 and is a mm or so smaller on blade length, but the X1000 is back in the saddle again and has been running 12 hours today without a hitch, and I am writing this post on it.
It's actually kind of nice that this was NOT an X1000 issue, but a Radeon fan issue.
It's nice to be back using my favorite computer! And thanks again for the help on this forum, don't know what I'd do without you guys.
Pocasset, Massachusetts USA