what's the metal ring for ?

M

Mike

I just bought a coolermaster case.
On mall my other cases, there is a metal ring
with all the wires from the front panel to the
motherboard wrapped twice through the metal ring.

This case has the metal ring in the hardware bag
(not installed) the wires I am talking about
are the reset button, speaker, on-off switch
and power led and hdd led activity lights.

all those wires are looped around this ring on
my other computer cases.

I have two questions

1. what is this metal ring for ?

2. how do I properly install the ring, if I need it ?


Thanks
Mike
 
P

Paul

"Mike" said:
I just bought a coolermaster case.
On mall my other cases, there is a metal ring
with all the wires from the front panel to the
motherboard wrapped twice through the metal ring.

This case has the metal ring in the hardware bag
(not installed) the wires I am talking about
are the reset button, speaker, on-off switch
and power led and hdd led activity lights.

all those wires are looped around this ring on
my other computer cases.

I have two questions

1. what is this metal ring for ?

2. how do I properly install the ring, if I need it ?


Thanks
Mike

The ring could be made of ferrite. The ferrite is resistive
at high frequencies, and when a wire is wrapped around it,
the ferrite helps attenuate conducted emissions. In other
words, if you receive broadcast television with rabbit
ears, you'll see fewer herringbone lines on the screen, if
you use the ring, and wrap the wires around it. It also helps
you with the neighbours, so they don't call the FCC on you.
(Note - this is all in theory. In practice, the computer may
already be electrically quiet enough as is. But when you
see lines on the television, then every little bit of
preventive measures helps.)

http://www.fair-rite.com/newfair/faqfer.htm
(Some pictures of common forms in here...)
http://www.fair-rite.com/newfair/pdf/15th_Edition_Fair-Rite_Catalog_Cable_and_Connector.pdf

If you still see lines on your TV screen, you can also try
a power strip with filters built-in. (The filters in that
case are probably common mode chokes or PI filters, but not
likely to be ferrite rings.) I have that problem with
a couple of computers - apparently there aren't good enough
filters in the power supply, and external filters such as those
in the power strip, help reduce interference from the
computer with the television.

Note that the ring is intended for wires with low speed signals
on them. If you were to wrap a SATA cable or an ethernet wire
on a ring, you may find the error rate goes up, or communication
stops altogether. If you are unsure as to when to use the ring,
just don't use it. Your example, of wrapping the reset cable,
speaker cable, on-off switch, and LED wires, is a perfectly good
example of wires suitable for use with the ring. All of those
wires are quite low speed, and their function will not be
impeded by the ring.

HTH,
Paul
 
G

George Pontis

Mike said:
I just bought a coolermaster case.
On mall my other cases, there is a metal ring
with all the wires from the front panel to the
motherboard wrapped twice through the metal ring.

This case has the metal ring in the hardware bag
(not installed) the wires I am talking about
are the reset button, speaker, on-off switch
and power led and hdd led activity lights.

all those wires are looped around this ring on
my other computer cases.

I have two questions

1. what is this metal ring for ?

2. how do I properly install the ring, if I need it ?


Thanks
Mike

It is to reduce the amount of radio frequency noise that escapes from
your computer. Since you will not have any practical way to tell if it
is needed, and that there is no downside to using the ring, just go
ahead and install it when you assemble the case. Grab all the pairs of
wires and feed them through the eye, loop around the outside and
through the eye once more. Then connect the wires as usual.

George

--
 

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