This may be perfectly normal. Recall that the PSU outputs 5 volts even when
"off" so that the computer's wake-up functions can work. That means it's
still rectifying the incoming AC, chopping it at an ultrasonic frequency,
and running it through a transformer. I've always believed -- without a lot
of proof -- that ultrasonic transformer whine can sound like a hiss, because
the vibration has irregular components that are audible.

"hupjack" hupjack_nospamtoday_yahoo.com wrote in message
...
I've got your joe-average ATX case and I can hear a faint hissing coming
from the power supply even after the computer is shut down. I can kill
the sound by flipping the switch on the back of the power supply (which
kills power into the psu). I know "faint hissing" isn't super
descriptive, but can anybody tell me whether I should be afraid of this
psu? Is in the process of frying itself? its capacitor? or some other
part that I'd rather not fry? Or is it no big deal and some psus make a
bit of noise? I don't have any past experience with this hardware, so I'm
afraid I can't say if it used to be quieter or not.

Thanks,
Ethan

--

To e-mail me, replace "_nospamtoday_" with the "@" symbol when replying to
my address.