Opening ATCS 840 is very easy since both side panels are fastened using thumbscrews. In Figure 11 you can have an overall look from inside ATCS 840.

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Figure 11: Inside ATCS 840.

In Figure 12 you see the top part of the case with its two 230 mm fans and the 120 mm rear fan. As explained, when installing a power supply on the top you need to remove at least one of the top fans. They both need to be removed if you want to install a water-cooling radiator based on two or three 120 mm fans directly inside the case. The case comes with four plastic parts to allow the installation of such radiator.

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Figure 12: Top fans.

On the bottom part of the case (Figure 13) we have a washable dust filter for the power supply fan (which should be installed with its fan facing down) and a place for installing an optional 120 mm fan that doesn’t come with the case.

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Figure 13: Bottom part.

Daughter boards are fastened to the case using regular screws. No screwless mechanism or thumbscrews are provided. We think Cooler Master should have included thumbscrews here, since we are talking about a high-quality case. As already mentioned, this case use meshed covers here.

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Figure 14: Expansion slots.