I would think that at least the fan in the back should be running. If
ALL of the fans are hooked up maybe the noise level would be too high.
electricitym

I would like to see the fan in the back
running as well as it usually cools the power supply. Front fans are
usually set to add cooling to the disk(s) if they are mounted near
them.

Thanks to the two of you for this. You have given me an idea. As this
computer even with the one ARCTIC COOLER fan is not quiet enough to have
it in the same room as a microphone, I might as well have the other
three fans running just to ensure the greatest longevity of the machine!
Unfortunately, for recording, I am going to have to put the computer
in an adjacent room (with extension cables) anyway. So does having
four fans running sound reasonable - or unnecessary? If, as Jim
suggests, the two front fans are meant to cool the disks mounted above
them, then at the moment those disks aren't being cooled at all - unless
that ARCTIC COOLER fan up near the top of the back is just so great it's
cooling everything!

Ellie.