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Buying and Installing DIMMs

The HP Pavilion PC motherboards that support the DIMM form factor allow for system memory expansion by installing DIMM modules into the available DIMM sockets and/or replacing installed DIMM modules with higher memory units. Systems that use DDR-DIMMs are discussed later, but the installation and removal procedure is the same as described in the previous project.

Note that the DIMM SDRAM modules used in the HP Pavilion PCs

  • Can be 16 MB, 32 MB, 64 MB, 128 MB, 256 MB, and 512 MB, but may be limited by the motherboard as outlined in Table 6.1.

  • Have 168 pins.

  • Are Intel v 1.0-compliant.

  • May be single-sided or double-sided.

  • Are 3.3 volts.

  • Are 64-bit unbuffered.

  • Support 4-clock (which allows 4 chips to be accessed in each clock cycle).

  • The clock speed is dependent on the system. Refer to Table 6.1. Clock speeds for DIMMs are 66 MHz, 100 MHz, or 133 MHz, depending on the motherboard and CPU installed.

HP motherboards that use DIMMs have either two or three memory module slots. This allows for the maximum memory configurations listed in Table 6.2. "Type 1 through type 7" is not official terminology. I use it to simplify the examples below. The number of slots and the maximum size of the DIMM modules supported depend on the motherboard.

Table 6.2 Maximum memory configurations for DIMMs.

System Type

DIMM slots

Maximum DIMM module size

Maximum memory allowed

Type 1

2

2 x 128 MB

256 MB

Type 2

3

3 x 128 MB

384 MB

Type 3

2

2 x 256 MB

512 MB

Type 4

3

3 x 256 MB

768 MB

Type 5

2

2 x 512 MB

1.0 GB

Type 6

3

3 x 512 MB

1.5 GB

Type 7

4

4 x 512 MB

2.0 GB


There are many different combinations for installing DIMMs in your system. Here are some examples.

  • Example 1. Assume the system is type 1 and has a 32 MB DIMM in the first slot. This system allows expansion to 256 MB. If you want full expansion, you'll need to remove the 32 MB DIMM and install two 128 MB DIMMs. If you want to keep the 32 MB DIMM, you could add a 128 MB DIMM for a total of 160 MB of memory (32 + 128), which is suitable for running Windows 98. Keep in mind that some motherboards don't allow modules larger than 128 MB or 256 MB in a slot. Also, move the smaller DIMM to the second slot and put the larger DIMM in the first slot. Doing so is not essential, but may improve access speed.

  • Example 2. Assume the system is type 2 and has 32 MB DIMMs in the first and second slots (64 MB total). You can add a 128 MB DIMM for a total of 192 MB of memory. You could also remove one or both of the old DIMMs and populate two or three of the slots with 128 MB memory modules. Rearrange the modules so the larger modules are in the first slots for more efficient memory access.

  • Example 3. Assume the system is type 3 and has a 128 MB memory module in the first slot. You want to run Windows XP with 256 MB of memory. You can install a 128 MB memory module in the second slot, but if the small price difference between a 128 and 256 MB memory module doesn't bother you, buy the 256 MB module and add it to your system for a total of 384 MB of memory (128 + 256). Rearrange the modules so the larger modules are in the first slots for more efficient memory access.

  • Example 4. Assume the system is a type 4 and had a 32 MB DIMM in the first slot. A friend has two 64 MB DIMMs left over after upgrading her computer. You install the two modules in your computer to increase your memory to 160 MB (64 + 64 + 32). Yeah! Free upgrade. As usual, rearrange the modules to the larger DIMMs are in the first slots.

As you can see, it is a matter of juggling memory modules, possibly keeping what you have or removing it and expanding your system to the maximum memory. Remember to recycle your old memory to friends. The procedure for removing and installing DIMMs was covered in the previous project. Refer there now for instructions.

Remember that in Type 1 cases, the height of the DIMM modules must not exceed 1 inch. Taller modules will not clear the drive bay when the motherboard panel is swung back into place.

For more information, refer to the following Web page:

HP Pavilion PCs – Memory Specifications and How to Upgrade RAM:http://www.hp.com/cposupport/personal_computing/support_doc/bph03886.html.

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