We must confess the junior Carbide series model, 300R, did not impress us much. Yes, it can accommodate longest expansion cards and is quite easy to handle, but every system case in this price category is handy whereas longest cards aren’t used by everyone. Its out-of-box ventilation isn't perfect. Even if the front fan is moved into the best position, the 300R is inferior to the other Carbide products in terms of cooling. And additional fans you may want to install to improve the situation will eliminate the small price difference between this model and the 400R which is better in many respects. The front-panel dust filter and the handier fastening of the bottom filter are the only solutions that are better in this model than in its series mates.
The 400R is the real deal. It is worth every cent of its $99.99 price tag. At a mere $10 more than the 300R, it provides a larger and better-ventilated disk rack, has an eye-catching appearance thanks to the highlighting of the side fans, and features a number of smaller design improvements (flared side panels, vibration-absorbing spacers for fans, scratch-resistant paint, etc). The problem of this model is that the nonstandard connection of the front fans prevents you from regulating them with your mainboard settings. It is only the flagship model of the Carbide series that has a controller for those fans. Thus, users who value silence are directed to the 500R (or even to the more expensive Obsidian 550D with the same chassis but extra soundproofing). The lack of the speed regulation looks like a marketing trick to us.
The Carbide 500R adds the following to the advantages of the 400R model: modular design of the disk rack, a huge side fan with highlighting, a 3-way speed controller, vibration-absorbing spacers for optional 140mm fans, and a more attractive exterior (especially in the white version which is not available with the 400R). The benefits of the 500R will cost you an extra $40 compared to the 400R, which may seem somewhat too much for a 200mm fan, a simple speed controller, etc. The white paint doesn’t cost more, as opposed to the Graphite 600T.
But if we put the internal competition within the Carbide series aside, the 500R at its current price looks quite a competitive offer. Free from downsides, it is easy to assemble, quiet and well-ventilated right out of its box!