PaulE.Masons post(clipped):--

<<<< Final symptoms on power-up were: Fans on, two to three second warmup, then
fans off and siren.>>>>

I would suggest the following:--
(1)check the RAM memory sticks.
(2)remove the power connector to your mobo from your power supply box and try re-seating and booting up
(3)if both the above do not give any clue then remove EVERYTHING except keyboard, mouse, and video and try booting.

HTH and good luck---Venkat

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