Installing Memory Modules in a PC
Installing Memory Modules in a Computer:
Before you open the system case and begin installing new memory modules in your PC, regardless of whether you are replacing existing modules or inserting additional memory, there are a few precautions you should take:
Back up the system: Anytime you open the system case to add, remove, or replace components such as the processor, memory, power supply, or disk drive, you should create a backup of the hard disk drive, especially if you are working on the hard disk drive itself. You never know what can happen, and it’s better to be safe than to lose everything on the hard disk. If you have a large hard disk, you should use a tape drive, writable CD-ROM, back up across a network (perhaps the Internet), or use lots and lots of diskettes.
Protect against ESD: Always protect the PC against ESD (electrostatic discharge), the static electricity that can build up in the PC and you. It doesn’t take much in the way of an ESD charge to damage a memory module. Work in an antistatic environment and wear an antistatic wrist or ankle strap.
Work in a Well-lighted Area: Most of the components in the PC are small, especially the screws. Anytime you open the system case, you should do so in a work area with plenty of direct light. If this is not possible, then have a reliable flashlight on hand to help you see what you are doing and to help you find all of the screws you drop inside the case.
Protect the Memory Module: Most memory modules, SIMMs and DIMMs, come packaged in an antistatic sleeve (see Figure 7-8). Keep all memory modules in their protective packaging right up to the moment you are ready to install them. Also, place any removed modules into a protective sleeve immediately after removing them from the PC, and never stack unprotected memory modules on top of each other.
Handle modules only by their edges: Avoid touching the module’s connectors and components. It doesn’t take much in the way of ESD to damage the module. ESD you can feel is ten times more powerful than a charge that will damage an electronic circuit, such as a memory module.
Installing a SIMM in a PC:
Before you begin installing a SIMM module, be sure that you have the right SIMM for your system. There aren’t a lot of choices, but the ones you have are significant to your PC’s acceptance of the new memory:
Match the number of pins: The number of pins on the SIMM must match that of the motherboard socket. A 72-pin module will not fit into a 30-pin socket. However, using a SIMM converter add-in board, 30-pin modules can be adapted into a 72-pin socket.
Parity versus nonparity: Verify whether your system uses parity or nonparity memory and avoid mixing and matching. A nonparity system will take a parity memory module and simply ignore the parity bits, but it is always better to match like components together. A parity system will take ECC memory.
Match the metal: Avoid mixing gold connectors with tin sockets and vice versa. Doing so could lead to intermittent memory problems or a failed memory module.
Installing a DIMM in a PC:
Compared to a SIMM, a DIMM module presents a few additional challenges and choices. First, a DIMM is installed straight down into its socket on the motherboard. The module has alignment notches like a SIMM, but it is inserted vertically into its socket and pressed into place. The TheDIMMmounting socket has locking tabs that should snap into place when the module is correctly installed.
All DIMMs have 168 pins, except the SODIMM used inside portable computers. So that worry is removed, but a DIMM has a few other options that must be matched to your system:
Voltage: DIMMs are available with 3.3v or 5v to match the voltage used on a motherboard.
Buffering: DIMM modules are available either as buffered or nonbuffered. Buffering adds a small amount of logic to a DIMM to increase its output flow.
Notching: DIMM modules have different alignment notches based on the combination of their voltage and buffering options. So, if a DIMM module will not fit into the socket on your motherboard, it is likely the wrong type and combination for your PC.