Kiwi Quiet P4 Cooling

Do-It-Yourself Systems
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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.

In future I'd do a couple more things:

  • 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.
  • 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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