Is it the torrid ring type (version 2) or the older black box type My old black box version 1 PSUs used to hum, but I've upgraded now.

Nick

On Jul 6, 2013, at 6:31 PM, "isoldeandisobelle" < isoldeisobelle@... > wrote:

> Hi gang -
>
> I have a 6U case and a 9U case, the 9U PSU hums (which changes in frequency when different modules are in use.) - the 6U does not do this.... is this ok
>
>


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