3.4 Preparing the Motherboard for Installation
3.4.4 Installing the CPU
Microprocessor installation is not a complicated process. Most problems occur when the chip is hastily installed or installed backwards, which causes the chip pins to break. It is important to handle the microprocessor with extreme care.

There are two main types of CPU interfaces. These are the socket type (such as socket 7) and the slot type (such as slot 1). Chapter 2 "How Computers Work", has more information regarding CPU interfaces. Socket 7 has been the standard interface, although the newer systems are now using different sockets. It is the only interface used by at least one generation of Intel Pentium processors (Pentium I) as well as AMD and Cyrix chips. Older technology processors chips, such as Intel P24T, P24D, 80486DX4, 80486DX2/DX/SX-SL, and 80486DX2/DX/SX or AMD AM486DX4/DX2/DX or Cyrix CX486DX2/DX/S and 5X86 processors, attach to the motherboard by means of a specially designed socket, commonly called socket 3. These technologies are quite old so it is unlikely that they will be encountered.

Slot type interfaces use a slot similar to expansion cards. Slot 1 is the Single Edge Contact (SEC) interface used only by the Intel Pentium II processor family. Therefore, the installation of the CPU will differ depending on the processor being used and the interface type.

This course gives instructions on how to install a socket 7 chip. All the newer socket type interfaces are derived from socket 7, differing mainly by the number of pins they have. The latest technologies, such as socket A (for AMD Athlon and Duron chips) and Socket 370 (for Celeron and some Pentium II and Pentium III chips) are installed using the same basic steps as socket 7.

The Step-by-Step Installation of the CPU
Almost all socket 7 systems make use of the Zero-Insertion Force (ZIF) socket. To install a socket 7 or similar chip, follow this general procedure:

Step 1 First, turn over the chip and inspect the pins to make sure none are damaged (bent or broken). All pins should stick straight out.
Step 2 Now, orient the chip by locating pin-1 on both the chip and the socket. Notice that the chip is always marked at pin-1. The mark might be a little different for different chips. For example, it might be a slightly notched corner, a little dot on the corner, a little mark at one of the pins under the chip, or more likely, a "missing" corner pin. On the socket itself, pin-1 is commonly identified by a notch on one corner, a big "1" or sometimes an arrow on the motherboard pointing to that particular corner of the socket. As always, consult the motherboard manual for additional guidance. Align pin-1 on the chip with pin1 on the socket for a correct installation.
Step 3 After correctly orienting the chip, open the ZIF socket. Shift the lever slightly away from the socket, from its default closed, level position and raise it to the open, vertical position. Do this with great care to avoid breaking the lever. If there is a little resistance on the way up, this is normal. When fully raised, the top part of the ZIF socket will slide over a bit.
Step 4 With the socket open, it is time to insert the processor. Aligning pin-1 according to the orientation that was determined in step 2, insert the processor chip into the socket so that all of the pins slide into the matching holes. With any ZIF socket, the CPU pins should slide easily into the corresponding holes in the socket. Generally, the chip can go in only one way. Avoid forcing the processor into the socket as the pins can be damaged.
Step 5 Double-check to make sure that there is no gap between the bottom of the CPU chip and the socket. If there is none, then the processor chip is properly inserted.
Step 6 Finally, to secure the installed chip, simply push the lever gently back down to the closed, level position. A little resistance may be felt, but the lever and ZIF socket should close fairly easy.

Configuring the CPU Voltage
Most motherboards are flexible enough to handle a variety of CPUs, but most CPUs are very particular about the amount of voltage they can handle. Therefore, once succeeding in installing the CPU, it is important to make sure that the right voltage is present for the proper performance of the processor. Pentium II and most current CPUs adjust automatically to the voltage, so they do not require voltage configuration. While this has been a great development, it still has to be done for some of the older CPUs. If the proper voltage is not set, total damage to the system could occur, or the whole system will never operate correctly. With some hands-on experience, voltage configuration for any motherboard can be set. Remember to keep grounded, check CPU specifications, and follow the motherboard manual.

The information needed for voltage setting should be contained in the "Jumper Settings and Connectors" section of the processor manual. CPU voltage varies between 1.8v and 3.5v. Dual voltage requirements accompany some CPUs. This means that two separate voltages, a core voltage and an I/O voltage, are required for these CPUs to function. The AMD-K6 CPU family, for example, requires dual voltage power for operation.