03 February 2013

How I made our computer quiet

One of the two (!) fans in our computer's power supply has been getting more and more raucous over the past few months. I don't know whether this means it was close to actually stopping, but it was certainly close to actually driving me crazy. So, somewhat out of character for me, I decided to finally try to do something about it. Big mistake.

I found the following three options for what to do.
  1. Lubricate the fan.
  2. Replace the fan.
  3. Replace the power supply.
I decided to replace the power supply. It seemed a little wasteful, but lubricating the fan didn't seem guaranteed to succeed and I was scared off of replacing the fan by warnings about capacitors holding a charge for hours.

A brief digression. I found it amusing to see, in an online discussion of what lubricant to use, a British person asking for the equivalent of "gun oil" since shops in his country don't commonly sell it, or sell guns, for that matter! (It was speculated that "sewing machine oil" would be similar.)

So I was determined to get a new power supply but not spend a huge amount of time figuring out what the best one would be. I fear I waste a lot of time shopping online for things, optimizing on margins that don't matter. Well it turns out it would have been worth spending some time figuring out what a correct one would have been, leaving aside the question of what the best one would have been.

I found some random site that offered a nice-looking lookup of power supply by computer name, and trusted it. Big mistake.

It turns out there has been a lot of evolution of the ATX power supply standard over the years. As is so often the case, there's a good Wikipedia article covering it. I only wish I had read it before plugging my new power supply in. (Digression: since it is so often the case that there is a good Wikipedia article about things, I've recently donated to Wikipedia, and plan to do so regularly, and encourage you to do so, too, if you find it useful.)

So, I plugged my new power supply in, and everything seemed fine, but when I came back a few hours later, there was a strange smell in the room and the computer was off and would not turn back on, even with the old-but-noisy power supply plugged back in. Woops.

So, making good on the promise implicit in the title of this post, that's how I made our computer quiet. Very quiet. One might even say silent.

I lack some combination of the skill and the inclination to figure out exactly what happened, but my not-too-wild guess is that you shouldn't plug a 20-pin power supply into a 24-pin motherboard. I guess I was hoping that if it wouldn't work, it just wouldn't work. Meaning, I hoped that if it wouldn't work, it would fail in the following three ways.

  1. obviously
  2. immediately
  3. non-destructively

Well, it did fail obviously. But not immediately, and not non-destructively.

Was my wishful thinking a product of "overly digital" thinking? Though digital systems have plenty of non-obvious, non-immediate, destructive failure modes, somehow I think analog systems have even more.

And power supplies are about as analog as you can get. In fact, they're not even analog: they're power! Power is the analog of nothing! Or, put it this way, I've never heard of power being used as the analog of anything. Voltage, certainly. Current even, sometimes. But power, never.

Returning from that digression, my point is, that what probably happened is that things did work, initially, and then once something heated up, over time, something on the motherboard melted or burned.

It turns out that those 4 extra pins are supplying "redundant" 3.3, 5, and 12 V lines, as well as ground. Not having them forces the other pins to carry more than their "fair share" of the current. Unfortunately I guess the weak point in the system was on the motherboard, not in the power supply. Otherwise plugging the old power supply back in would have worked.

So then I set about spending several should-have-been-sleeping hours researching the current offerings of Dell and HP. In other words, my mistake has led me to the most wasteful option, the following implicit option number 4.
  • Replace entire computer.
Whenever I research buying a new computer I'm always shocked by the way in which each manufacturer divides their products into confusing, overlapping market segments, where it seems like the same computer is being offered over a 4x price range with the only obvious difference being different case design. (It turns out there are deeper differences, you just have to spend several hours to start to get a grasp of them. Whether these differences justify the 4x price range... well, if the market bears it, I guess the answer is revealed to be "yes.")

So, I'll be spending a little quality time over the next few days setting up a hopefully-nice new Windows 8 machine.

Still to be determined whether I will shell out $100 to upgrade from Windows 8 to Windows 8 Pro. I am curious to try to run Ubuntu under the "Hyper-V" virtualization built into Pro, but probably I should just save $100 and use VirtualBox, like I do with great success and ease on MacOS on my MacBook Pro.

Also, will we ever want to connect to the machine using Remote Desktop? For that, you need Pro.

Decisions, decisions.

But at least these decisions are back in the realm of software, where I feel more comfortable.

Because if there's one take-home lesson from this experience, it is that I shouldn't have felt comfortable in the realm of power. She is a cruel mistress, the analog of nothing.


  1. Oh, Ben, that was a mistake. You should have talked to me first. One of my projects while I was at Google was to pretty much become an expert on PC power supplies.

    You could have dropped maybe $120 on a high-quality 80+ "Gold" unit (yes, with 24 pin recent) with a large fan -- or even a fanless one. Large fan is better because it can get the same airflow but by turning slower. High efficiency (80+ gold, silver, etc) is better because more efficient means less heat to dissipate, meaning less need for fan.

    Under most circumstances, the fan in my PSU doesn't turn at all. When the computer is drawing a lot of power, it turns on a bit, but almost inaudibly.

    To build a machine with a fanless PSU, you also need to know that the rest of the machine can work without forced airflow. This is extremely atypical. You have to remember that the PSU fan is cooling not only the PSU, but the whole system.

    Anyway, sorry about your machine. You can probably get a new motherboard.

  2. David, what brand would you suggest?