Inside the Carbide 678C
Opening the front door of the 678C and you are greeted by a massive dust filter which is held in place magnetically with two bottom tabs to ensure it can swivel away from the top. The front fan is installed in the top location here, but one thing to take note of is, as I mentioned previously, you can now see that the only gap for aspiration in the front of the 678C is the bottom of the front panel. While this may make for a pretty aesthetic, we had seen situations before where thermal performance was less than stellar due to lacking airflow. Also of note is we took out the cover for the 5.25" drive bay, which is indeed in place and ready to install should you still use something like an optical media.
Here we have the inside of the chassis now without the glass panel. As you can see, you did not miss much by looking through the panel as everything is pretty wide open. The drive trays to the right are removable for an even more wide-open area, and there are two hidden 3.5" trays below the PSU shroud you can use. If using the opening in the front of the PSU shroud for a very thick radiator, removal of the drive trays may be necessary.
The CPU cutout on the motherboard tray is massive and should be fine for any cooler I have ever had hands-on time with. While you may not be able to tell from this shot quickly, the motherboard tray is recessed, and where you see the vertical cable grommets is where it protrudes upwards as you move toward the front. This is why the grommets are so far right from the standoffs to allow for EATX board fitment.
Here we see the fan mounting form the backside and the single installed fan in place. You will notice that the HDD trays are in front of the fan mounting, but they are vented to allow air through, so their restriction should be minimal. To fit the H100i, we use for our standard testbench; we will install the top fan below the front fan and have both as intake into the front.
The top solid panel we saw before had sound deadening material on the bottom of it, helping keep the interior noise from coming out. Under the solid panel, you will notice that there is also a magnetic dust filter in place for you to use if you install ventilation up top. Funny enough Corsair fits one of the 140mm fans up top, and for new builders, they may not notice that their fan is blowing onto a solid panel.
Removing the magnetic filter allows us to see the preinstalled fan along with the slotted mounting for both 140mm and 120mm fans. I do like that Corsair moved the motherboard down a bit from the top, making interference by top-mounted cooling a little less of an issue.
The PSU shroud is long and well ventilated. Here you can see, as mentioned previously, that the front-most area is cut out to allow for thicker radiators to pass through. The HDD cages are in the way for maximum thickness and would have to be removed if going that extreme. The PSU shroud has a few close to motherboard cable pass-through holes which do not use grommets and one a bit more outboard, which does. This will likely be used for GPU power cables.