In today's world of constant change, the most frequently performed task by a computer professional is to upgrade old systems to the latest technologies. This ability to expand and upgrade a computer can prolong the life and utility of a system. However, sometimes even the simple addition of a new piece of software can lead to hardware conflicts and the subsequent need for an upgrade, as a computer owner tries to squeeze one more year out of "old faithful." This lesson discusses many aspects of computer hardware upgrades.
After this lesson, you will be able to:
Estimated lesson time: 30 minutes
- Describe the principles behind upgrading a computer.
- Define the limits of and expectations for upgrading a system.
Run the mboard video located in the demos folder on the CD accompanying this book to view a presentation of a personal computer's motherboard subsystem.
Run the assembly video located in the demos folder on the CD accompanying this book to view a presentation of components being assembled into a personal computer.
As discussed in Lesson 1, before you begin to upgrade any computer, you need to document the system. You should create and maintain files that document all computers for which you are responsible. Figure 14.1 provides a sample configuration sheet. Use it as a model to create your own.
Figure 14.1 Sample configuration sheet
Does this computer have enough memory? This is the question that most frequently causes users to seek a computer upgrade. As programs and hardware get faster and are required to process more graphics and animation, the need for memory is as important as the need for speed.
Memory upgrades are perhaps the simplest to perform, but they can be very confusing without advance planning. Purchasing the right memory for the job is more than half the process of the upgrade. Before installing memory, there are five things to consider:
The best source of information—which should be checked before obtaining memory—is the documentation that comes with the computer's motherboard. This source will generally list the type of memory required, how many SIMMs are required, and their location on the motherboard. If this information is not available, open the case and look. Some documentation provides a chart that includes exactly what memory has been installed and what is needed to upgrade to a given level. The following table gives you an idea of the kind of chart you might come across.
|On-board||Bank 0||Bank 1||Total|
|8 MB||8 MB|
|8 MB||4 MB||4 MB||16 MB|
|8 MB||8 MB||8 MB||24 MB|
|8 MB||16 MB||16 MB||40 MB|
|8 MB||32 MB||32 MB||72 MB|
|Disabled||64 MB||64 MB||128 MB|
You can add memory with SIMMs (single inline memory modules) or DIMMs (dual inline memory modules).
SIMMs are provided in two basic, physical formats: a 30-pin and a 72-pin chip. Format is the first consideration, because the chips must fit into the motherboard. This configuration, along with the size of the processor, determines how many SIMMs are required to fill one bank.
The 30-pin formats contain memory in 8-bit chunks. This means that a 32-bit processor requires four SIMMs to fill one bank. Typical 32-bit processors consist of two banks of SIMMs and therefore eight slots. (See Figure 14.2.)
Figure 14.2 30-pin SIMM
A 72-pin format is larger and supplies memory in 32-bit chunks. Only one SIMM is required for a 32-bit machine. A Pentium processor has a 64-bit data path and requires a 72-pin SIMM. (See Figure 14.3.)
Figure 14.3 72-pin SIMM
Memory is normally sold in multiples of 8 MB. However, some machines will have 8 MB of "on-board" memory (usually soldered in place on the motherboard). When memory is soldered in place, it cannot be changed but this should not be considered a problem; it can be disabled. A computer equipped with this on-board memory can provide 8 MB of memory to the system without having any SIMMs installed in the slots. For such computers, installing 16 MB of RAM too would yield a total of 24 MB of RAM; if 64 MB were to be added, the total RAM would be 72 MB, and so on. In general, the idea of hardwiring memory on a system has died out on desktop PCs.
DIMMs are much easier than SIMMS to install or remove, because they require only one card, which is simply pushed into a module slot. The "key" cut into the edge that goes into the slot prevents the card from being inserted the wrong way. The one problem you face is choosing from the wide variety of memory types available. When ordering a new DIMM, you must know exactly the memory type supported by the system. DIMMs are found in larger memory sizes than SIMMs, ranging to 256MB and beyond for single cards.
Memory speed is the amount of time required to access data and is measured in nanoseconds (ns); each nanosecond equals one billionth of a second. Two important considerations arise when addressing memory speed:
Typical chip speeds are 50, 60, 70, and 80 nanoseconds. Be sure to check the motherboard documentation or the existing chips to determine the correct speed to use.
The EDO RAM (extended data out read only memory) chip is used extensively with Pentium processors. This chip can improve read times and overall performance by up to 30 percent. This performance gain is possible because the chip continues to output data from one address while setting up a new address.
Parity is used to check the reliability of data. It requires one additional bit (chip). Memory can be purchased with or without parity. With parity, it will cost about 10 percent more. Be sure to check the machine specifications or the existing chips to determine if parity is required. Parity and nonparity chips cannot be mixed; however, some computers allow parity to be turned on or off (BIOS setup).
Cache memory can be found as either L1 or L2. The L1 cache is built into the processor and cannot be changed. The L2 cache, on the other hand, can be either built into the processor, or built onto the motherboard, sometimes both. In most cases, cache memory is fixed, but some machines allow L2 cache to be upgraded or expanded. Cache memory is sometimes found on older motherboard (as DIPPs—dual in-line packages). Check the motherboard documentation to determine what, if any, upgrades can be made to the cache.
You need to take special care when installing DIPP chips. They are sensitive to ESD, can easily be installed backwards (look for pin 1 alignment), and the pins can be broken or bent during insertion.
Installing RAM is a simple process. The only problem is that the slots are not always easily accessible. Sometimes you will need to relocate wires temporarily or even remove expansion cards. This simple procedure usually works:
Figure 14.4 Installing a SIMM
The computer should recognize the new memory and either make the correction or automatically go to the setup program. In many cases, you need only exit setup to save the changes.
Installing a new CPU is becoming less common as the prices of new motherboard/ CPU combinations (and even new machines) continue to drop. In many cases, installing additional memory is a more effective upgrade than installing a new CPU. Still, as a technician, you need to know how to update the CPU in an existing machine.
In many cases, upgrading a CPU is as simple as removing the old one and inserting the new one. First, you need to determine whether the CPU can be upgraded and, if so, to what? The answer to this question lies in the motherboard. The motherboard must have the appropriate socket, data bus, address bus, and crystal to support the new CPU. Consult the documentation that comes with the motherboard—this documentation usually contains a table that defines which CPUs can be installed. If you are unable to find the documentation, or the processor that you want to install is not listed (because it's of newer vintage than the documentation), you will need to consult the motherboard manufacturer either through the company's Web site or with a phone call to the company's tech support department. Be sure to check on any required jumper settings and BIOS upgrades at the same time.
A small upgrade, going from one level of the same CPU family to another, is usually no problem. But if you want to upgrade a 386 to a Pentium, or a Pentium to a Pentium III, a new motherboard is the only answer. The same is true if the CPUs are coming from different chip makers. Refer to Chapter 4, Lesson 2: Replacing and Upgrading Chips, for possible scenarios.
Perhaps the most difficult part of upgrading a CPU is determining the limits imposed by the motherboard. But after the decision is made and you have the new processor in hand, the actual installation is quite easy. Follow this general procedure to install a CPU:
Some CPU upgrades also require the installation of a new voltage regulator and/or cooling fan. Be sure to check the motherboard and CPU documentation for this possibility. Failure to install these parts with the new CPU might destroy the CPU.
If you are working with a motherboard that has the ability to hold more than one CPU, both CPUs must be of the same type and from the same manufacturer if more than one is actually installed. In addition, on Pentium II and later systems, most such motherboards have a special card that must be inserted in any empty CPU slot, and the appropriate slot must be used for a single CPU configuration.
Installing an expansion card is one of the most common system upgrades. Adding faster video cards, more ports, or improving sound quality are common reasons for plugging in a new card. (See Figure 14.5.) Before installing (or purchasing) an expansion card, it is a good idea to make sure it will work in the system to be upgraded, and that appropriate drivers are available for the operating system to be used.
Figure 14.5 Motherboard and expansion card
Ask these questions first:
After you have determined that the expansion card will work, the installation is a simple three-step process:
Step 1 (IRQ and I/O setup) is perhaps the most confusing and frustrating part. This is especially true if the computer has not been properly documented.
Be sure to cover all slots. A missing expansion-slot cover can cause a computer to overheat. Be sure that no screws or other items are left loose inside the case that could possibly short out a component after the case is closed.
A card that is not Plug and Play capable is a bit more complicated than one that is.
Figure 14.6 Switches
Figure 14.7 Jumpers
Figure 14.8 Installing an expansion card
The latest technology available for installing expansion cards is called Plug and Play. This is an independent set of specifications developed by a group of hardware and software companies that allow the user to make configuration changes with minimal adjustment. Simply install the card, turn on the computer, and use the device.
In order for Plug and Play to work, the device must be able to identify itself and its system requirements to the system. The operating system will then set the device and make any other adjustments, such as reconfiguring other devices, as required. In order for a Plug and Play device to work immediately, you must be sure that the computer hardware—motherboard, BIOS, and other components—the operating system, and the device are Plug and Play-compliant.
If a device is Windows 95-compliant, it is Plug and Play-compliant, too, and can take full advantage of operating in a Windows 95 environment.
In many systems you must enable Plug and Plug features in the system CMOS. (Failure to have the right settings will make installing a Plug and Plug card a difficult task.)
Installing a new drive is not difficult. However, you must answer a few questions before purchasing a new drive:
Installing an IDE (Integrated Drive Electronics) drive will require some hardware and software preparation to get it running properly. Hardware preparation includes ensuring that you have the correct drive, a place to physically install it, and the proper cables to connect it. Software preparation includes at least a bootable MS-DOS disk containing a minimum of FORMAT and FDISK. A Windows 95 or 98 startup disk will do the job. If you don't already have such a disk, be sure to create one before removing the old drive. Follow these steps to install the drive:
Figure 14.9 Cable Connections
It might be advisable to set up and test a drive before final installation in the bay. Be careful to avoid ESD or placing the drive in a position that will cause excessive heat build-up. Large capacity drives, especially SCSI and older ESDI (Enhanced Small Device Interface) drives, can generate a lot of heat. It might be necessary to position a small fan to send a current of air over the drive's logic board when running a hard disk drive out of a computer or drive case.
Some larger drives installed in older machines might require the use of disk-management software. This software is usually provided with the drive (in some cases, it's already loaded in the drive). Follow the instructions provided by the manufacturer to extract and use this software. It's especially important to document the use of such software, and to make sure it is included on any boot/rescue floppy you prepare for such a system.
To complete the installation:
The drive is now ready for software to be installed.
Installing a new motherboard is one way to completely overhaul a computer. (See Figure 14.10.) In many cases, it is the most inexpensive way to get a new computer. This type of upgrade usually works best with IBM clones. Many of the larger manufacturers use proprietary motherboards that can only be replaced with one made by the same manufacturer to ensure compatibility with other components.
Figure 14.10 Motherboard
Before deciding to undertake this major overhaul, there are several questions to answer:
Installing a new motherboard is a major task and requires complete disassembly, reassembly, and setup of the computer and all its devices. You will put everything covered so far in this lesson into practice when you replace a motherboard. The best advice is to prepare everything ahead of time and to take good notes while disassembling the old motherboard.
Replacing a motherboard is probably the most difficult task (from the perspective of physically replacing parts) that a computer technician will take on. It amounts to no less than building a computer, because it will, in many cases, require complete disassembly first. Although complex, if you carry out the following procedure one step at a time, you should not face any problems.
Figure 14.11 Motherboard in case
The following points summarize the main elements of this lesson: