Man, I love 1U servers! They’re just so sleek and small. But, damn, are they loud! I recently picked up an HP ProLiant DL320 G6. It was almost great, except for those 16,000 RPM fans, whirring at ~67 dBA each. So, this weekend, I replaced its stock fans with much quieter fans. And since /r/homelab is all abuzz about silencing 1U servers, I thought I would share my process.

If You’re Lucky…

If you’re lucky (or proactively smart), your motherboard will have standard 3-pin or 4-pin fan headers. If so, swap the fans. Congratulations! You’re done.

Unfortunately, I wasn’t so lucky. The HP DL320 G6 fan headers looked something like this:

proprietary fan headers

That, boys and girls, is a pair of 6-pin, 8-wire, fan headers.

What You’ll Need

The Tools

  • wire stripper
  • 9V or 12V battery
  • Battery holder with leads
  • FIRE!
  • loud, annoying, proprietary fan
  • quiet, awesome, standard fan
  • a demo fan
  • heatshrink tubes

For the “quiet, awesome, standard fan,” I used a SUNON HA40201V4-0000C-C99. These 40mm suckers are (in my opinion) the best bang for my buck. They push 5.5 CFM at 12.8 dBA. That’s damn near silent!

DISCLAIMER

You should know: as with any exchange, there is a trade-off. By replacing loud, high-performance fans with practically-silent fans, you (and I) run the risk of overheating the servers, if the fans cannot efficiently cool them. I am not responsible for your servers or any damage you may incur.

Step 1: Research

The first part of any big problem is to research your problem. I googled around, searching for others with DL320’s. My search led me to a couple of helpful articles, but, for the most part, I was on my own. I also stumbled upon the spec sheet for the original fan. From all these, I gathered at least three potential pinouts–two of which are shown below:

fan pinouts

I could, of course, just use a multimeter to read out the voltages of the fan headers. Except, I don’t really know how to use a multimeter, or at least not enough to know I won’t short-circuit my motherboard. “Help, I used a digital multimeter on my motherboard’s fan headers.” I came across that too, in my search for answer.

Step 2: Trial

With a few pinouts at hand, I stripped away the wire jacket of the stock fan. I attached the 9V battery to the battery holder with leads. Then, I used the leads to test out which pins/wires powered the fan. That was easy. Most of the pinouts that I had were right about this: red is usually power, and black is usually GND. The pinouts also mostly agreed on the blue wire being the tachometer wire, although blue is less standard. So, I cut the plugs off the stock fan and the demo fan, and twist-tied the matching wires according to one of the pinouts. Then I tried it out:

trial demo fan

Step 3: Error (err–Warning)

fan not redundant warning

As you can imagine, this is the POST telling me that it expected two fans, but only saw one, so it left me off with a warning. I was surprised at this. Had there not even been a fan plugged into that header, it would have refused to boot. I’ve even heard that some HP systems will use the fan’s tachometer to ensure that its PWM signal has the right effect–spinning at the appropriate, expected RPM.

Step 4: Repeat

sunon test

demo+sunon test

It took a couple of attempts to figure out the correct pinout–the pinout that would suppress the POST warnings. For all you future modders:

Pin #ColorPurpose
1OrangePower (+12V)
2BlackGND (0V)
2GrayGND (0V)
3RedPower (+12V)
4BlueTachometer
5YellowPWM?
5WhitePWM?
6GreenTachometer

Notice that some wires doubled-up on some pins. I suspect it’s because it’s the same voltage running across, and therefore they don’t need a separate pin? I don’t know–I’m not an electrical engineer.

After I figured out the correct pinout, I used the heatshrink tube to seal up the twisted ends of the wires and then installed the fans.

Some may choose to solder. I don’t solder well, and it’s a big pain in the ass. Heatshrink tube is good enough (if your twisted ends are secure and not loose), easy, and clean. But, I am, admittedly, an hobbyist/amateur, not a professional, so take my advice for what it is.

sunons

installed sunons

Since those fans really couldn’t be screwed into the case, I had to get a little creative. I’m still not thrilled with it, but it’ll do.

zip ties

done

Oh, and let’s add chambers!

During my research on stacked fans, I read that the air from the front fans could cause interference with the rear fans. I think that’s why those stacked Delta fans were clamped together–to form a chamber. Yeah, I could’ve removed those front three fans, but I didn’t want the POST to throw warnings. So, instead, I made “chambers”:

chambers

Result

It’s much quieter now. And, the cores run from 29°C - 35°C at idle (with inlet ambient air at about ~22°C). I don’t yet know how it’ll do under stress. All in all, this was quiet an endeavor, and an excellent learning opportunity. I always love having done these projects after I’ve done them, but they end up being such a pain-in-the-ass that I hope to never do them again lol.