This is in reference to another thread :
Sounds like a PSU issue to me...
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It started happening again.....One of my harddrives started the spindown/spinup cycle during 100% folding.
This time I used google-fu first.
Low voltage does not cause this.Low voltage would stop a HDD dead , not cause spin cycling.
From what I've seen , a harddrive spinning down then spinning up on a cycle is most likely due to 'Thermal recalibration'... While it can be a sign of a dying HDD , in my case it appears to be 'too hot'.
I'll be increasing the cooling on my HDD area and testing this.
more soon.