NZXT has been opting for as much metal as with the NZXT H510i with their cases for quite some time, which has them skip any top or front panels made out of plastic; one of the signature elements of the H series, the H510i is no different. It offers the same sleek, straight, and understated look as the whole H lineup. Looking at the front, there is not much else than a solid piece of steel that comes with a hard bend at the top as it wraps around and becomes the top piece. If you look closely, you will find a subtle brand logo on the bottom of the front. In the rear, the enclosure looks quite traditional, with the PSU bay at the bottom.
The main side of the H510i consists of a tempered glass panel that takes up around 70% of the area, while the rest is simply part of the case as the unit employs a metal shroud to separate the PSU and 3.5" drives from the rest of the system. On the opposing side, you will find a solid panel with the exception of an inch-wide airstrip towards the front; it is necessary to give any fans or a cooling system in the front access to clean air.
At the bottom, the power supply's opening comes with two sets of mounting holes, which means you may pick a unit of your choice without running into any limitations. Above that are the seven horizontal and two vertical expansion slots. You have to remove the two vertical slots to access to the remaining ones. In the very top is a 120 mm retail-grade exhaust fan that is set to push air out the back of the H510i.
You will find a pretty standard set of I/O consisting of a single audio combo plug, a USB-C port, and a single purple USB 3.1 connector. A round power button with a ring-shaped LED on one side and a tiny reset button on the other completes the set. Towards the rear of the steel top, you will find a fairly intricate opening with another 120 mm fan pre-installed, which is, once again, set to push air out of the chassis. To protect the PSU from dirt and grime, an easily removable dust filter can be found on the underside.