Seating the memory
When orienting the cooler, also consider your system memory. The tall heat spreaders on some memory modules can interfere with CPU coolers that hang over a motherboard's DIMM slots. The heatsink on our Corsair A70 tower stays out of the way, but one of its two fans encroaches on the first couple slots on our motherboard.
The overhang is a problem because our Corsair Dominator Platinum DIMMs have taller-than-normal circuit boards in addition to beefy heat spreaders. Since the A70 can get by with a single fan, we'll ditch the one that gets in the way. If we wanted to keep the second fan, we could switch to low-profile memory modules.
Most desktop systems use dual-channel memory. For optimal performance, one DIMM per channel is required, ideally from a matched pair of modules. Motherboards typically come with four slots—two per channel. If you're installing only two DIMMs, check the motherboard manual for guidance on which slots to use. Two-DIMM configs typically drop into slots labeled A1 and B1. The letters signify the channel, while the numbers reveal the order in which the slots should be populated.
Before installing the memory, make sure the plastic retention tabs at the ends of the DIMM slots are open. The tabs should lean away from the slots. Some motherboards, including the Asus P8Z77-V we're using, have retention tabs on only one end of the memory slots.
DIMMs are keyed to fit only one way, making installation simple. Line up the notch in the bottom edge of the memory module with the separator near the middle of the slot, and then slide the module into place. If it rocks back and forth like a see-saw, the DIMM is oriented the wrong way. When the DIMM is the right way around, it should slip into the slot easily. Apply even downward pressure to both sides of the top edge to seat the module fully in the slot.
Seating the memory should cause the retention tabs to swing up, locking the DIMM in place. If that doesn't happen, flip the tabs with your finger. They should hook into notches in the vertical edges of the memory module.
Preparing the enclosure
Although the internals of every case are different, there are two predominant layouts in the world of PC towers: traditional and upside-down designs. The former puts the PSU above the motherboard, while the latter situates it below. Upside-down layouts are particularly popular these days.
The Corsair Obsidian Series 650D enclosure we're using for our build is an upside-down design, and it's pretty representative of the breed. Inside, the chassis is filled with builder-friendly features like grommeted cable routing holes, access to the underside of the CPU socket, and tool-free drive bays. On the outside, there are multiple front-panel ports for peripherals, plus a dock that allows hard drives and SSDs to be plugged into the chassis' top panel. Those external features connect directly to the motherboard, which we'll install in a moment. First, we have to prepare the case.
Expose the case's internals by removing the side panels and setting them aside. Most modern cases use tool-free latching mechanisms or thumb screws to secure their side panels. If your case doesn't, you'll need a screwdriver.
Don't worry if your enclosure has a removable panel on only the left side. You'll still be able to get everything into the chassis, but wiring it all cleanly will be more difficult. Right side panels provide access to the back side of the motherboard tray, which is the best place to hide cabling.
Motherboards are mounted onto the tray using a series of raised posts that line up with holes in the circuit board. On the 650D, these posts are already affixed to the tray. If the motherboard posts aren't pre-installed in your case, they can be found in the accompanying bundle of screws and accessories. The posts look like short screws with long, hexagonal heads.
Special tools aren't required to install the posts, which can be screwed in with your bare hands. Make sure the posts are tight and that they match the hole pattern of your motherboard. Misplaced posts can short exposed solder points on the bottom of the board, and the ensuing snap, crackle, and pop has the potential to damage system components.
ATX motherboards typically have nine screw holes. You don't have to use them all, but we'd recommend it. You'll need to use at least six or seven posts to prevent the board from flexing when installing expansion cards and other hardware, and it doesn't take much time to add the remaining ones.
Next, rummage around in the motherboard box and extract the I/O shield, a shiny metal piece riddled with holes. Some cases come with their own I/O shields, but odds are they won't match the port layout of your motherboard. You can pop out an existing I/O shield by pushing it into the case from the outside. Install the new one by pressing it into the rectangular cut-out next to the motherboard tray.
Make sure the shield is the right way around. Look at the port cluster on the motherboard, imagine it sitting in the case, and you should be able to figure out the correct orientation.
When snapping the shield into place, be careful not to slice your fingers on the little metal tabs protruding near each port opening. Some of these tabs, like the ones on top of the Ethernet and DVI ports on the shield pictured above, stick out quite a bit. To prevent the motherboard ports from getting hung up on the tabs, bend them up slightly.