Drive mounting hardware and grounding

[Don Freeman]

When physically mounting the drives (HD/CD/DVD) to the case is it necessary
to have metal to metal contact with the case for grounding? The reason I
ask is that I would like to try putting rubber/vinyl spacers on the screws
to help cut down on vibrations generated by the drive. Might not accomplish
much of a difference but I would like to try.

 

[Alan Kakareka]

When physically mounting the drives (HD/CD/DVD) to the case is it

necessary to have metal to metal contact with the case for grounding? The
reason I ask is that I would like to try putting rubber/vinyl spacers on
the screws to help cut down on vibrations generated by the drive. Might
not accomplish much of a difference but I would like to try.

Another thing you must consider, if you put rubber in between the HDD and
the case - the heat can't go out of HDD to the case, so install additional
cooling.
When HDD is on rubber - it is not stable as it would in metal-to-metal and
it will increase seek time of your HDD - yes, it will have lower perfomance
(maybe a few % down)

--
Alan Kakareka
Data Recovery Service
786-253-8286 cell
http://www.247recovery.com
--

 

[Don Freeman]

Another thing you must consider, if you put rubber in between the HDD and
the case - the heat can't go out of HDD to the case, so install additional
cooling.

That's a concern I hadn't thought about, thanks. So far I have a 120 rear
panel fan and a 80 side panel (both output). I plan on adding a front panel
intake which I can position in front of the HD. Then move the case temp
sensor near the HD to monitor but I'm unsure of what the threshold should be
and from what distance.

When HDD is on rubber - it is not stable as it would in metal-to-metal and
it will increase seek time of your HDD - yes, it will have lower
perfomance (maybe a few % down)

It wasn't going to suspend it on rubber, just use washers (~1/8" thick)
around the screws, (it wouldn't be as loose as the suggestion in a current
issue of one of the PC magazines: to suspend it in the case with rubber
bands.) Wouldn't dampen a lot of the noise but shouldn't effect the
stability either. If that winds up being the case though I would discard
the idea, seek time in more important then whatever noise I might dampen.

 

[Guest]

When physically mounting the drives (HD/CD/DVD) to the case is it necessary
to have metal to metal contact with the case for grounding? The reason I
ask is that I would like to try putting rubber/vinyl spacers on the screws
to help cut down on vibrations generated by the drive. Might not accomplish
much of a difference but I would like to try.

There's no problem with the grounding, which is handled by the black
wires of the power cable, nor should the rubbery material increase the
heat, unless the drive is currently mounted flush against thick pieces
of aluminum (they'd likely need grease or a thin layer of rubbery
material to assure good thermal contact). Secure the screws since they
can work loose from vibration; use weak Loctite, like #242 (this is
blue, but don't go by color alone since some of the strongest Loctite
is also blue) or lock nuts, but best are vibration isolators with metal
sleeves in the middle (hardware stores sell them or at least suitable
sleeves or tubing). Seagate doesn't like shock mounts because it
increases the settling time of the head seeks.

 

[Rod Speed]

When physically mounting the drives (HD/CD/DVD) to the case is it
necessary to have metal to metal contact with the case for grounding?

Varys with the drive. Plenty ground the case thru the power connector.

And a few have a spade terminal that can be used to ground the drive too.

 

[johns]

When physically mounting the drives (HD/CD/DVD) to the case is it necessary
to have metal to metal contact with the case for grounding?

No. Grounding is a Black Art. Ideally, you want all grounds
in your system to take a short single wire path to a common
point IN THE POWER SUPPLY. You do not want ground
loops running around your case. They can generate voltage
drops across the case, and actually push your power
supply above ground ... thereby generating high currents
in sensitive digital circuits located at different points in
the computer .. i.e mobo, video card, super-high-expensive
data acquisition cards .... You especially do not want to
case ground your mobo at the standoffs ( big deal ). If
you use an aluminum standoff, it will corrode, and return
currents will cause a voltage drop across the standoff and
burn your mobo at that point ... not to mention push the
mobo ground. If you mount your hard drives in rubber .. like
in an Antec case, and you are worried about the drive
getting hot, replace your cpu fan with one of the 92 mm
cpu fans that also blow sideways on the drives and ram.
Cost you about $15, and runs much quieter. So, your
idea grounds in your computer are the ground wires on
the power supply connectors which run back to the
power supply, and connect to a single bus in the supply.
Your case is AC safety grounded by the power supply
metal box. Don't rubber mount that thing

johns

 

[JAD]

contrary to johns and his BS....been using grommets since the dawn of
time..nothing, nada, zip, zilch, has ever adversely happened. cons - 0
pros - cutting vibration noise (especially with opticals)

 

[Rod Speed]

Don Freeman wrote

No. Grounding is a Black Art. Ideally, you want all grounds
in your system to take a short single wire path to a common
point IN THE POWER SUPPLY. You do not want ground
loops running around your case.

Thats analog mentality, doesnt apply to PCs.

They can generate voltage drops across the case,

Nope, because there is no current flowing.

and actually push your power supply above ground ...
Nope.

thereby generating high currents in sensitive digital circuits
located at different points in the computer .. i.e mobo, video card,
Nope.

super-high-expensive data acquisition cards ....

He's unlikely to have any of those.

You especially do not want to case ground
your mobo at the standoffs ( big deal ).

Oh bullshit.

If you use an aluminum standoff, it will corrode,

No it wont, because there wont be any currents.

and return currents will cause a voltage drop across
the standoff and burn your mobo at that point ...

There wont be any currents.

not to mention push the mobo ground.

Wrong again. Thats done with the PSU ground lines.

If you mount your hard drives in rubber .. like in an
Antec case, and you are worried about the drive
getting hot, replace your cpu fan with one of the 92 mm
cpu fans that also blow sideways on the drives and ram.
Cost you about $15, and runs much quieter. So, your
idea grounds in your computer are the ground wires on
the power supply connectors which run back to the
power supply, and connect to a single bus in the supply.

Pity about the ground connections in the internal cables which dont.

Your case is AC safety grounded by the power
supply metal box. Don't rubber mount that thing

Doesnt matter if you do, its connected to the grounds internally.

 

[Michael]

Someone please correct me if I'm wrong, but I would think that if
grounding is required at these points the screws would provide a path
(the head contacting the case and the body contacting the drive
enclosure). Therefore spacers would have no negative effect.

 

[Stephen]

When physically mounting the drives (HD/CD/DVD) to the case is it necessary
to have metal to metal contact with the case for grounding? The reason I
ask is that I would like to try putting rubber/vinyl spacers on the screws
to help cut down on vibrations generated by the drive. Might not accomplish
much of a difference but I would like to try.

The Antec P180 case isolates all the hard drives via rubber mounts.
Just make sure the drives have sufficient air flow across them due to
the loss of the case as a heat sink.

Stephen
--

 

[Stephen]

No. Grounding is a Black Art. Ideally, you want all grounds

Black art only to the clueless.

in your system to take a short single wire path to a common
point IN THE POWER SUPPLY. You do not want ground
loops running around your case. They can generate voltage
drops across the case, and actually push your power
supply above ground ... thereby generating high currents

The case is also a ground in all properly designed power supplies.

in sensitive digital circuits located at different points in
the computer .. i.e mobo, video card, super-high-expensive
data acquisition cards .... You especially do not want to
case ground your mobo at the standoffs ( big deal ). If

Then why do motherboards provide a ground at all the mounting points?

Stephen

--

 

[Rod Speed]

Someone please correct me if I'm wrong, but I would think that if grounding is required
at these points the screws would provide a path (the head contacting the case and the
body contacting the drive enclosure).

Not if you have rubber/vinyl spacers for the screws,
particularly if you have one under the screw head.

If you dont have one under the screw head, you
wont be doing much to cut down the vibrations.

Therefore spacers would have no negative effect.

Fraid so if the drive case isnt grounded via the power connector.

 

[Brian K]

The Antec P180 case isolates all the hard drives via rubber mounts.
Just make sure the drives have sufficient air flow across them due to
the loss of the case as a heat sink.

Stephen

Interesting. I just put a system into an Ultra Wizard case. For some
unknown reason Western Digital failed to include mounting screws with my
HDD. I simply used some of the extra screws that came with the case.
These screws have sort of a built-in metal washer as part of the screw
head. I used my ratchet screw driver to tighten them snugly but not
overly so. Guess what? No vibrations. The new Mach Speed, AMD 64
3700+ system I built is 100% more quiet than my old P-III unit.

--
________
To email me, Edit "blog" from my email address.
Brian M. Kochera
"Some mistakes are too much fun to only make once!"
View My Web Page: http://home.earthlink.net/~brian1951

 

[johns]

Heh! First job out of college ... Corning Electronics
Research Labs ..then .. Bower Electronics Research
... then .. Physics Dept, NCSU, MicroElectronics
Research ... it goes on like that

johns

 

[johns]

Then why do motherboards provide a ground at all the mounting points?

Stephen

They don't. That is a pressure relief pad
that prevents crushing the multilayer mobo.
The dummies asssumed it was a ground
.... and then they go and "ground" it to an
aluminum case .. you know, the kind of
connection that was outlawed in homes
because it corrodes and starts fires
If you want to see a real grounding hassle
sometime, send the millivolt output from
a data acquisition instrument about 80
feet on a coax cable to a data collector
card in your computer. The difference
in ground potential in a building just going
80 feet can be several volts and a very
high ground current on the cable shield.
The proper way to ground sensitive integrated
circuits, is to cut the cable shield at one end,
and ground each box locally to its own
power supply. Sometimes you even have to
use a nulling voltage from a very stable source
to cancel out grounding differences. I've done
it with a zener and Hg battery.

johns

 

[Rod Speed]

Heh! First job out of college ... Corning Electronics
Research Labs ..then .. Bower Electronics Research
.. then .. Physics Dept, NCSU, MicroElectronics
Research ... it goes on like that

Clearly no use on the basics like the fact that ALL
hard drives dont have a single common star ground.
Pity about the ground in the cable.

In spades with the motherboard mounting holes which
almost always have grounding lands round them. They
wouldnt have that if the manufacturer didnt want the
motherboard grounded there, they'd just have pcb instead.

 

[Rod Speed]

They don't. That is a pressure relief pad
that prevents crushing the multilayer mobo.

Like hell it is. If the manufacturer didnt want them
grounded, there's just be pcb there, no land at all.

And have fun explaining how my systems work fine.
I prefer to use the tapped hex spacers for mounting
the motherboard at all mounting points.

The dummies asssumed it was a ground
... and then they go and "ground" it to an
aluminum case .. you know, the kind of
connection that was outlawed in homes
because it corrodes and starts fires

With mains currents. You dont get any of those
between the motherboard and the case.

If you want to see a real grounding hassle sometime,
send the millivolt output from a data acquisition
instrument about 80 feet on a coax cable to a
data collector card in your computer.

Irrelevant to systems that dont have any A/D cards.

You clearly dont have a clue about the difference
between analog and digital systems.

And even you should have noticed that CAT5 works fine
without any need to have the system grounds connected.

And TV capture cards work fine without a single star ground too.

The difference in ground potential in a building
just going 80 feet can be several volts and a
very high ground current on the cable shield.

Pity PCs are different internally.

The proper way to ground sensitive integrated
circuits, is to cut the cable shield at one end, and
ground each box locally to its own power supply.

How odd that hard drives dont do it that way and still work fine.

Sometimes you even have to use a nulling voltage from
a very stable source to cancel out grounding differences.

Not with digital systems you dont.

I've done it with a zener and Hg battery.

Not necessary inside a PC.

 

[larry moe 'n curly]

The case is also a ground in all properly designed power supplies.

Earth ground but not necessarily the same as the ground that connects
to the black wires. This shouldn't matter unless the PSU is installed
in a plastic case, and I've seen only one instance of this. However
I've seen two other PSUs designed so they could have easily been built
to keep the case and other ground separate.