How To Build A PC: From Component Selection To Installation

Step 10: Build The Platform (CPU, Cooler, And DRAM)

Many technicians refer to the CPU, motherboard, DRAM and graphics as a platform. These parts can be assembled and tested outside of a case by connecting a power supply and power button. And, except for a discrete (separate) graphics card, they can usually be inserted as an assembly into an empty enclosure.

Socketed processors have followed a common theme for at least 20 years: an arrow on one corner of the CPU aligns to another arrow on the CPU socket. This is the first method manufacturers use to assure proper orientation, but AMD also uses missing pins with blocked interface holes to further prevent improper installation.

CPU pins are easy to bend, so if you're really rushing through the motions, it's certainly possible to force a processor into its socket the wrong way, smashing its pins in the process. With the tension lever released as shown, the CPU should literally drop into the socket under its own weight, with no force applied. These are known as Zero Insertion Force (ZIF) sockets.

After checking to make sure the CPU is fully inserted, press the tension lever into the horizontal position to lock it in place.

LGA processors have edge notches to prevent incorrect installation in addition to being marked with an arrow as a visual guide. A load plate holds the pinless CPU tight against socketed contacts, called lands. One or two locking levers apply the load.

After making sure that the CPU is correctly installed (as shown above), lower the steel load plate over the CPU and rotate the wire clamp into its locked position.

Thermal interface material (also known as thermal compound, paste, or grease) fills tiny spaces between the CPU and its cooler to assure optimal heat transfer. Most factory-supplied coolers have a stiff factory-applied TIM that becomes soft when heated by the CPU, but other coolers require the manual application of thermal transfer grease or paste.

Igor Wallossek’s article on thermal paste installation shows a perfectly acceptable way to add today’s thick thermal materials without creating a mess. A small blob in the center of the sink will indeed spread as shown in the above photos, and thermal softening will likely spread it even more as the system is used. But I like to maximize contact surface area all the way to the corners, so I usually put a slight smear of paste around ¼” from each corner in addition to the small blob in the middle. My old method of dabbing it on worked only with the low-viscosity pastes of the past.

Excess paste will squirt out around the edges of the CPU, so it's important not to apply so much as to create a mess. Cleaning pastes out of crevices can be particularly difficult, and becomes necessary when using certain metallic thermal solutions.

Clip-on CPU coolers are still used by AMD for its Socket AM3+ and FM2+ processors, and the clip is still compatible with most of the firm’s older socket interfaces. With the cooler in position, slip the non-levered end over the corresponding plastic hook, then repeat the process on the levered end. Finish the installation by flipping the lever to apply pressure.

Pinned-on CPU coolers use mounting holes rather than the more traditional clip bracket. Introduced with Intel’s LGA 775 package and retained through the company's modern LGA 1150 interface, installation requires pushing each pin into the corresponding motherboard hole until a click is felt or heard.

The lower pin (translucent white, above) is hollow, split on one end, and has barbs on the split end. This part goes through the mounting hole first. The upper pin (black, above) protrudes through a hole in the lower pin’s center to wedge the barbs apart. Twisting the top of the pin ninety-degrees counterclockwise unlocks the spring pressure, allowing the cooler to be removed.

Because a counterclockwise twist defeats the latching mechanism, check that all pins are properly twisted fully-clockwise before attaching the cooler.

Screw-on coolers solve the problem of fragile plastic pins and the four points of motherboard strain by using screws and a load-spreading support plate. This greater security and motherboard protection is particularly useful with large and heavy coolers that require increased contact pressure across the CPU’s heat spreader. The support plates are typically designed to fit Intel's four-pin mounting holes, or replace AMD's clip-style brackets. Intel’s LGA 2011 motherboards ship with a support plate already installed, and many coolers also ship with a second set of mounting screws to use its threaded holes.

Because the support plate must be placed behind the motherboard, these coolers should be mounted before the motherboard is installed into the chassis. Many cases have an access hole in their motherboard trays specifically for this purpose, but it’s usually easier to reach the screws with the motherboard unobstructed by case walls.

Installing RAM

System memory is keyed so that it only fits into the slot one way. Because this key is off-center, backwards modules cannot be fully inserted. Check to make sure that the notch in the module's contact area aligns with the slot's key, and press each module into the slot until a click is heard or felt from the latches. Fully seating modules may require a relatively significant amount of pressure.

Our configuration called for a pair of modules in corresponding slots to enable dual-channel mode. Check your motherboard manual to see which slots should be used for this performance-enhancing orientation.

Also note the slot numbers, which are usually written on the board, and compare them to the module installation order outlined in the motherboard manual. This was particularly critical with LGA 1156- and LGA 1366-based motherboards because they relied on a DIMM in the second slot of each channel for termination, though many LGA 1150 and 2011 motherboards aren’t as fussy.