FreeNAS 9.10 Lab Build – Part 3

In Part 2 of my FreeNAS 9.10 build series, I installed my newly flashed Dell PERC H200 LSI 9211-8i card into my primary management host to try out FreeNAS as a VM with PCI passthrough.

After opening the case to do some rewiring I was totally shocked at how hot the little aluminum heatsink on the card was. This thing wasn’t just hot – it was scalding hot. Hot enough to invoke the subconscious and instinctive reaction pull your finger away from the heatsink. If I had to guess, I’d say that heatsink was at least 90’C or hotter.

Although it was surprising, I had to remind myself that this adapter is not a consumer grade card and does have an airflow requirement for it to run reliably. Dell’s H200 user guide says very little about the cooling requirements, unfortunately, but some of the Dell PowerEdge servers that support the H200 classify it as a ‘25W TDP’ card. That may not sound like a lot of thermal output, but when you consider most of that is concentrated on an area the size of a dime, it’s a lot to dissipate.

In most rackmount type cases, a minimum amount of front-to-back airflow is usually directed across all of the PCI-Express slots, but in my large Phanteks Enthoo Pro, there happens to be very little in this area with the default fan configuration.

After perusing around online, I could see that this was not an uncommon problem among SAS 2008 based adapters – including the popular IBM M1015 – and that in some circumstances the card could even overheat under heavy load. Considering how hot mine was while sitting idle, I can only imagine.

Even though I’ll only be using this card in a lab, I do want to ensure it runs reliably and lives a long life. It seemed that there were a few possible solutions I could pursue:

  1. Add a small 40mm fan to the heatsink.
  2. Replace the tiny heatsink with something larger.
  3. Find a way to increase the airflow in this area of the case.

The third option appealed to me most – mainly because I hate small fans. They usually have an annoying ‘whine’ to them as they need to spin at a higher RPM and they can be pretty unreliable. I’d also expect the width of the fan to block the adjoining PCI-Express slot as well.

So after taking a look through my spare parts, I came across an old Noctua 92mm PWM fan collecting dust. Although I think Noctua’s marketing is a bit over the top, I have been using their fans for many years and can attest to their high quality and quiet operation.

After MacGyver’ing a couple of thumbscrews and metal brackets I could get the fan into the perfect position. Also, because it’s a PWM modulated fan, it spins down with the rest of the system fans and is pretty much inaudible at under 1000RPM.

Even though there feels like there is barely any airflow coming from the Noctua NF-B9 fan at reduced RPM, it’s enough to dissipate the hot air from around the heatsink fins and the heatsink is now only warm to the touch! It really did make a huge difference.

Problem solved. Hopefully whatever case I ultimately use for my FreeNAS build will not have these sorts of airflow dead spots, but at least there could be a simple solution.

FreeNAS 9.10 Lab Build Series:

Part 1 – Defining the requirements and flashing the Dell PERC H200 SAS card.
Part 2 – FreeNAS and VMware PCI passthrough testing.
Part 3 – Cooling the toasty Dell PERC H200.
Part 4 – A close look at the Dell PowerEdge T110.
Part 5 – Completing the hardware build.

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