Hello

I assume you mean a mechanical hum. Right If so, then it should be
related to the method how the powersupply is fixed to the housing.

Florian

On 07.07.13 00:31 , isoldeandisobelle 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
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>