Noctua is known for making high-end, high-quality fans and air coolers, which it has been doing for over 20 years, recently expanding into AIOs. However, it appears that there were a few questions regarding its PC case compatibility database, which some PC DIYers say don’t match the data from the manufacturer’s website. The company cleared this up in a blog post, saying that it has undertaken its own measurements and it has determined that 56 of the more than 100 cases it has tested showed significant deviation from the details officially listed online.

The company gave two diverging situations of inaccurate official measurements. The first one is when the case is larger than what is actually written, which would allow PC builders to attach a larger cooler. Noctua said that the deviations aren’t minor, either. For example, the NZXT H2 Flow case is listed as being compatible with a maximum 75mm CPU cooler height, but the actual case can accommodate an air cooler up to 79mm. There’s also the Thermaltake TR100, which is 2.7mm larger than what the Thermaltake website says, and the Corsair Frame 4000D, which gives you 10mm of extra clearance.

This is a good thing, as any cooler you bought based on their website’s measurement means that it will definitely fit, but Noctua said that this is a missed opportunity. That’s because you could’ve bought a larger cooler that delivered more performance in the same case.

On the flip side, the company warned that there were also some cases that were actually smaller versus the numbers in their specifications. It cited two examples — the Asus Prime AP201 and the Lian Li B4-mATX. The former is 1.7mm shorter while the latter is 3.5mm shorter than what’s listed on their specific product pages.

This could to be a major issue, especially if you bought items that fitted the available space exactly, based on the manufacturer’s measurements. It would mean that these parts would either be touching the case panels, or worse, not allow them to close at all. If that’s the case, you’ll have to spend extra effort to return either the part or the case and get something that fits better.

The safest solution to this is for you to buy the PC case before you shop for the remaining parts of your build. This is especially true if you’re looking at the best mini-ITX cases, as the tight tolerances mean that you don’t have much margin if the numbers aren’t accurate. But by having the case physically available and measuring it yourself, you’re at least confident that what you’re buying will fit. Alternatively, you can check out Noctua’s compatibility search page, with the clearances of the cases in its database verified by its team.

This compatibility tool will give you peace of mind when shopping for the best cooler and is useful for confirming measurements even if you end up buying from another brand. But this begs the question — are the variations between official and actual measurements limited to the air coolers? Or are the numbers for other components, like the GPU, PSU, and other key components also inaccurate? Noctua’s website only covers coolers, so you’ll have to rely on other pages (or your own measurements) if you want some confirmation of a case’s specifications and clearances for other parts like GPUs and PSUs.