Performance Analysis

It seems our concerns regarding airflow restrictions were well founded. Starting with the solid roof option, the impact on the CPU is clear, as a delta T of 60°C puts the 678C way down the charts and next to cases where the fans are running at minimum speed, even when the three fans here are running at full speed. The GPU isn’t too bad at 53°C delta, a result which just manages to beat the Be Quiet! Silent Base 601.

We had hoped that swapping to the dust filtered roof segment would reduce temperatures, but the 2°C drop for the CPU is mediocre. That said, it’s enough to put it on par with the Be Quiet! case. Oddly, the GPU actually got 2°C warmer with the roof swapped to the more porous option.

Running a quick test with the front open saw temperatures drop drastically, with the CPU for example now hitting a delta T of 51°C, which would have placed it right near the top of the chart. This is pretty conclusive proof that the sealed up front is a real limiting factor in this case’s performance, and subsequently it’s reasonable to expect CPU and GPU fans to have to ramp up to compensate, thus somewhat defeating the low-noise credentials.

The SP140 fans are definitely loud at full speed (rated at 1,200 RPM with 10 percent deviance) and kick out a fair bit of air. The noise dampening does a decent job of containing it, and it’s important for fans designed to be used with speed controllers that there’s a nice RPM range, but overall the balance of noise versus cooling is just not that great with this chassis.

Conclusion

The Carbide 678C isn’t a bad case, but at £180 it is definitely overpriced. There are things that it does right, such as the ample storage options, PWM fan hub, hinged tempered glass side panel, and USB Type-C support. You could certainly build a powerful system into the case with relative ease, but that should be a given for a case at this price.

Sadly, the poor airflow situation impacts temperatures negatively, especially for the CPU. The plastic front panel, single-piece 2.5” mounting tray, and the notches/rails system used for the steel side panel all stand out as negatives too, and without other exciting features the 678C is just not that enticing, at least at the current asking price.