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With the fans taken care of for now, it became glaringly obvious
that the hard drive, which I had never noticed before in the shade of
that nasty stock Intel cooler, was now the loudest component.
So I uncharacteristically splashed out on a new drive, an 80GB Samsung. I
um-ed and ah-ed over the Samsung v. Seagate dilemma and gave in to the Samsung
with its superior quietness and three year warranty. I've not had
that positive an experience with Seagate's warranty handling in the past.
I got this thing home (it was the only part that didn't have to come
by aeroplane) and fired it up with a fresh Windows reinstall. Yes, the drive is real quiet alright. But what it lacks in noise it makes up for
in quite a fearsome vibration. I don't know whether this is standard for all
such 7200 rpm drives, for this model or just a quirk of this particular unit,
but left in the drive tray, or on my wooden floor, or on top of the case, it
instantly transferred this low frequency hum into the room. As it happened
I had been shopping around for some acoustic padding on the off chance that
I might want to line the case. All I could find
was this neoprene like stuff from the plastics store ( they call it yoga mat)
which is about 4 mm thick, and quite elastic. I put a couple of layers of
this under the drive and the vibration even penetrated that somewhat. So then
I made a sort of sling, popped the drive in it, and that finally put the horrid
hum to rest.
HDD anti-vibration sling.
So it seemed clear to me that the only solution to that hum with
the materials I had was to suspend the drive. I did wonder about sorbothane but it's hard
to get here and expensive. After a bit of tinkering
I came up with something else.
A better HDD anti-vibration solution.
Its a solution that compensated some for the loss of cooling from the case
contact, kept the drive earthed and yet also suspended securely enough to
prevent damage. I wanted the drive down low out of the worst of the case heat, near the cool incoming air and the enlarged intake
holes. I added copper heatsinks fashioned out of some 0.5mm sheet I had lying
around, and made the brackets out of stainless strap about 1mm thick by 25mm
wide. Its amazing how the use of the 25mm wide yoga mat material constrains
the back and forward motion almost completely, as opposed to the rubber bungy
cord approach seen elsewhere. The blue yoga mat stuff also has some sort of
internal reinforcing so while its elastic in its depth, the length and width
are not, hence it suspends well without giving.
Now that I've finished this thing I am left with the little doubt that maybe its
massive overkill, and I shouldn't I be wondering whether a drive ought
to vibrate so? It must have quite an unbalanced rotor to do that. Anyhow I've
heard others lament the Samsung vibration and so the cradle stays. I figure
the added heatsink increases the surface area of the drive three fold, and
in practice the drive temp seems to settle at around the case temperature.
Here's a drawing: (dimensions in cm). The metal "washers" that detain the 25mm wide
strips of yoga mat are just 1cm offcuts of the bracket material. The thing
is secured using standard case screws tapped into the bed of the case.
And the finished system.
Now with all the pieces put together, the main noise is a whooshy
sort of sound that is only audible when my office is quiet. As my office is
actually rather often quiet I can still hear those fans and still dream of
total silence. I read up on some recording studio acoustics and they recommend
placing soft padding on nearby hard surfaces to help absorb the whoosh of
the fans. I found some polyester house insulation and stuck some on the wall
behind the box and on the under side of my desk where the box sits. It did
help some, but didn't exactly help heat dissipation either.
And while I didn't notice it in the beginning the drive does have a high frequency squeal, I'd say around 18KHz
or so. Most people I know wouldn't hear it all; I've got really sensitive hearing.
Lastly it's worth mentioning that once the case lid went on and the
machine was buried under the desk, all the temps went back up a few degrees. Here's a plot showing opening the case about 85%
of the way along the plot. The motherboard temp dropped a degree and the CPU temp
dropped five degrees. I guess in my chain of heating, the CPU gets prewarmed
air from the HDD and across the motherboard.
Any reservations? Now that the machine is so quiet, I'm starting to miss those
familiar audible signs of my productivity. Its a bit eery really, and I especially
miss that familiar somehow comforting seek noise of the hard drive.
replace the case fan outlets with wire grills
drill a whole lot more holes in the front of the case to let more air in.
make a mark 2 fan speed controller, which has two speeds controlled by an adjustable temperature sensor threshold.
In future I'd do a couple more things:
look at a more upright, heatpipe served CPU cooler with a more direct heat path out of the case,
look at creating two completely separate airflow paths for the HDD / PSU and
the motherboard and CPU.
* * *
Complete Parts List (prices in NZ$)
Case: unknown plain vanilla mid tower ATX case (recycled) $0
MoB: P4V533-MX (second hand) w/CPU...
CPU: Intel P4 2.66A Northwood (second hand) $280
VGA: on board
RAM: ADATA 256MHz DDR400 $70
HDD: Samsung Spinpoint SP0802N $85
PSU: Acbel 300W API3PC49 $50
Optical: Liteon Combo SOHC-5232K $70
CPU cooler: Thermaltake Golf 325 $50
CPU fan: SilenX 80mm fan $26
Case fan: Titan 80mm $8
Speed control: DIY $8
HDD suspension: DIY $5
Total NZ$652, say about US$400
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