> > Most of the energy going into a hard drive ends up as heat in the 
> > chips & resistors, the rest in the spinning platters.
> 
> Surprisingly, it's the other way round. A significant 
> proportion of heat (> 50%) generated by a hard drive is 
> caused by air friction and bearing friction. This was told me 
> by an engineer who worked at Seagate and would be in a 
> position to know.


You're right, of course, that 12v rail is there for a reason.

Anyhoo, my point way that the power going in gets converted mostly to heat
(electronics & motor), some is stored in the moving platters (& motor
spindle) and a bit to light if you're lucky enough to get a LED or two.

Once the power is off, the platters will run down due to friction.  I'm not
sure drive platters make good flywheels, not much mass.  That's still a tiny
bit of heat generated.

The light from the LED will get absorbed into the case, a bit more heat.
You could angle your drives so the LEDs beam out the window into space, but
I don't think this will have much impact on his cooling bill.

Tony

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