Upgrading Memory (RAM)

HP and Compaq Desktop PCs - Upgrading Memory (RAM)
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In this document:
Installing memory

What to do if problems occur after installing memory

Windows Vista and memory

DIMM, SO-DIMM, and RIMM requirements for HP and Compaq computers

Video example about installing additional memory



This document pertains to HP and Compaq desktop computers.

This document provides information and step-by-step instructions on how to upgrade random-access memory (RAM). Upgrading memory inside the computer helps the central processing unit (CPU) process information faster, and improves system performance. Read all instructions carefully before attempting memory installation.



NOTE: Do not purchase memory modules until you know the type of memory used by the computer, the maximum amount of memory the computer can use, and the memory slot configuration.

Installing memory
Use the following steps to install memory in an HP or a Compaq desktop computer:



NOTE: Important! You may find that your HP or Compaq computer is able to support a physical installation of 4 GB or more memory. However, this maximum memory may be further limited by the operating system not being able to address the full range of physical memory. For 32-bit operating systems, Windows Vista and XP 32-bit editions can address approximately 3.3 GB. This limitation is present on all 32-bit hardware and 32-bit operating systems and is not limited to HP and Compaq systems.


Step 1: Finding memory information for your model
Important memory upgrade information is in the specifications document for your HP computer. To find product specifications, browse to the Product Information category on the support page for your computer model. Alternatively, you can search for your Product Specifications by doing the following:


In the Search field (or Questions or keywords field) at the top of this page, enter your computer model number, a space, and the word "specification."
For example, if you owned a Compaq Presario Media Center SR1838NX Desktop computer, you would enter:

SR1838NX specification

Click the link on the search results page that matches the Product Specifications for your computer model.

Refer to the "Memory" section within the Product Specifications document for memory information specific to your computer.

The specifications should have three important references to memory: amount of memory installed, maximum memory allowed, and type of memory. Write down this information; it will be useful when purchasing memory and when performing the next steps.


Step 2: Verify how much memory can be added
Use the following steps to find the exact memory configuration and how much memory should be purchased and installed:


Turn off the computer.

Turn on the computer and immediately press the F1 or F10 key repeatedly until a BIOS Setup Screen appears (some computers may use a different key, such as Esc, or F3).

From the Main screen look at the Installed Memory line. This is the total amount of memory currently installed and the speed at which it is currently operating.

Next, look at the Memory Bank information. The number next to each memory bank is the amount of memory for the module that is installed in that bank.


Figure 1: Example of BIOS memory information



You can also use the memory bank information to determine if a particular memory slot (bank) is empty.

To find the total amount of RAM that can be added, subtract the amount of RAM currently in the computer from the maximum amount of memory the computer can hold. For example, a computer has 256 MB of RAM. If the maximum amount of memory the computer can hold is 512 MB, then 256 MB is the amount of RAM that can be added.

To find the amount of RAM per slot, divide the maximum amount of memory that the computer can hold with the number of memory slots on the motherboard. Usually, this is the maximum amount for each memory socket. For example, if the computer is capable of holding a maximum of 1024 MB (1 G) of memory and the motherboard has four memory slots, install 256 MB (or less) memory modules per slot.

Obtain new memory modules keeping with the specifications.


Step 3: Open the access panel
Use the following steps to open the case:



WARNING: The edges of metal panels can cut skin. Be careful not to slide skin along any interior metal edge of the computer.



CAUTION: This product contains components that are easily damaged by electrostatic discharge (ESD). To reduce the chance of ESD damage, work over a non-carpeted floor, use a static dissipative work surface (like a conductive foam pad), and wear an ESD wrist strap that is connected to a grounded surface, like the metal frame of a computer.


Turn off the computer and unplug all cables, except for power, and write down each cable location.

Unplug the power cable and press the Power button.

If possible, move the computer to a clear, flat, stable work surface over an uncarpeted floor.

Remove the panel retaining screws.


Figure 2: Screw locations (your model may look different)



Slide off the panel to expose the inside of the computer.


Figure 3: Panel removal (your model may look different)



If opening the case is difficult, search for a support article that specifically pertains to your computer. In the Search field (or Questions or keywords field) at the top of this page, enter your computer model number, a space, and the words "opening the case."


Step 4: Determine if memory needs to be removed
Use the following steps to locate the memory sockets:


Look inside the computer and locate the memory modules on the motherboard. Memory modules are long thin boards, short in height, that stick up from the motherboard at a 90 degree angle.


Figure 4: Typical memory location (your computer may look different)



Do one of the following, depending on the socket configuration.


If the computer has an open socket, continue to Step 6 to add an additional memory module into the open socket.

If the computer does not have an empty socket, use Step 5 to remove a memory or continuity module. This has to be done before adding a new memory module. Account for how much memory will be removed before purchasing your upgraded memory module(s).



Step 5: Remove a memory or continuity module
Continuity modules do not contain memory, but are placeholders to close the memory circuit. Use the following steps to remove a memory or continuity module:


Pull out, and then press down on the holding clips that retain the memory modules. The memory modules should rise up slightly out the socket.


Figure 5: Opening memory module tabs



Pull out the memory or continuity module (for RIMMs) and place it in a static-safe container.


Step 6: Add a memory module
Use the following steps to insert a memory module into an empty socket:


If RIMMs are being used, keep the following items in mind when purchasing and installing modules:

The memory configuration of channel A (the first two sockets) and channel B (the second two sockets) must be identical.

Continuity RIMMs must fill any open memory sockets.

When a continuity RIMM is required, it should be installed into the second socket.

Align the memory module so the small notches on the lower edge line up with the raised marks in the socket.


Figure 6: Memory module installation


1 - DIMM (notches farther apart)

2 - RIMM (notches close together)


Push straight down on top ends of the memory module until the memory module is fully seated in the socket. The retaining clips on the ends of the socket lock into place when properly seated.


Step 7: Replace the cover
Use the following steps to replace the cover:


Slide movable bays and sections back into their original positions and secure with screws.

Align the panel or cover with the respective slots in the sides of the computer case.

Slide the panel or cover into place and tighten screws.


Figure 7: Panel replacement (your model may look different)



Reinstall cables. Plug the power cord in last.

Turn on the computer.

If the computer starts, perform Step 2 again to make sure that the new memory amount displays in the BIOS. If it does, you are done.

If the computer does not start, a beep code sounds, or the new memory amount does not appear in the BIOS, use the next section to troubleshoot the problem.


What to do if problems occur after installing memory
Try the following items if the computer cannot start or has memory errors (including beeps) after the computer starts:


Reseat the new memory module by repeating Step 3 through Step 7 of this document.

Remove the new memory module and clean the groove in the socket that the module sits in. Use a can of compressed air with a straw-type extender and safety glasses.

Check other cables connections inside the computer. Reseat any cables that were disconnected or partially unseated.

Remove the new memory module and try starting the computer again. If the computer starts, make sure you purchased the right type and compatible size of memory (see step 1 and step 2 ). You can remove and reference from the memory module that originally came installed in the computer.



Windows Vista and memory
Windows Vista comes in a variety of editions. All versions of Vista have a minimum memory requirement of 512 MB (1 GB to take advantage of certain premium features, such as Aero graphics). The maximum amount of memory depends on the edition used:

Edition of Windows Vista
Maximum addressable memory

Any 32-bit version of Vista editions
Approximately 3.3 GBs

Home Basic 64-bit
8 GBs

Home Premium 64-bit
16 GBs

Business 64-bit
128 GBs

Ultimate 64-bit
128 GBs




DIMM, SO-DIMM, and RIMM requirements for HP and Compaq computers

What is a DIMM?


Dual in-line memory modules (DIMMs) are small circuit boards that can hold groups of memory chips. DIMMs provide a wider path with two rows of pins on a side, allowing for faster data transfer than SIMMs. Like SIMMs, DIMMs may be manufactured single- or double-sided. DIMMs do not have to be added in pairs and can be mixed with other DIMMs that have the same number of pins. For example, a 64-megabyte (MB) DIMM can be added to the motherboard next to a 32 MB DIMM.


DIMM modules for the HP computer must meet the following requirements


The number of pins on the DIMM must match the socket type.

DDR memory requires a 184-pin slot and 1.8 operating voltage.

DDR2 memory is not compatible with DDR1 memory and requires a 240-pin slot and 2.5 operating voltage.

Synchronous dynamic random access memory (SDRAM): Only use DDR type SDRAM memory if the computer came with DDR-SDRAM.



NOTE: DIMMs can only operate as fast as the speed of the system bus. Also, if two or more DIMMs of different speeds are installed, the total memory only operates as fast as DIMM with the lowest speed.



What is a SO-DIMM?


Small outline dual inline memory modules are used in notebook computers and HP TouchSmart computers. They are smaller and thinner than other DIMMs, so are used when there is less space within a chassis.


SO-DIMM modules for the HP computer must meet the following requirements


The number of pins on the DIMM must match the socket type.

SO-DIMM memory requires a 200-pin slot.

DDR2 SO-DIMMs are not compatible with DDR1 DIMM and DDR2 DIMM memory modules.

With a computer running at a system bus of 533 MHz or 667 MHz, use a PC2-4200 (DDR2 DIMM 533) type.



What is dual channel mode (DDR)?


Double data rate (DDR) memory can operate in dual channel mode. The motherboard specifications of your computer should state if dual channel mode is supported. Dual channel memory mode provides increased performance over single channel mode.


The following requirements must be met for the DDR memory to function in dual channel mode:


Same density (256MB, 512MB, etc.)

Same DRAM chip technology (x8 or x16)

All either single-sided or dual-sided

Matched in both Channel A and Channel B memory channels




NOTE: Motherboards with Intel i945G or i945P chipsets; with DR2-667 memory modules using one Gigabit technology perform as DDR2-533 memory modules. If faster DDR2-667 memory modules are used, they must be 256 or 512 Megabit.


What is a RIMM?


RaMBus inline memory modules (RIMMs) are 184-pin memory boards that permit transfer rates of 600-800 MHz. RIMMs used with the Intel Pentium® 4 processors run on a 400 MHz system bus, allowing data transfer rates of 3.2 Gb/s.


RIMM modules for the HP computer must meet the following requirements


HP computers require PC600 or PC800 RDR modules (184-pin RaMBus dynamic Random access memory [RDRAM]).

Non-ECC (non error-correcting checking).

RAMBUS/Intel specification compliant.

All four RIMM sockets must be filled, either with a RIMM or with a continuity module called a Continuity RIMM (C-RIMM). C-RIMMs do not contain memory, but are placeholders to close the memory circuit.

RIMMs work in pairs, and they must be from the same vendor. RIMMs must also have the same memory size density within each channel.

When C-RIMMs fill empty sockets, they must be placed in the RIMM A2 and B2 sockets.

The RIMMs must be inserted in the RIMM A1 and B1 sockets.



Video example about installing additional memory
This video is provided as a supplement to the instructions in this document. For specific information, such as safety precautions and memory requirements, refer to the other sections of this document. Your computer may be different than the computer used in the video; however, the steps are generally the same and the video works as a great reference.


Download the video to the Windows desktop and open it from there. To download the video, right-click one of the following links and select Save Target As. Select Desktop as the destination for the file. After the video has downloaded, double-click the file on the desktop to open it.

The following are required to view this video:


Windows 98 or newer operating system

Windows Media Player version 6.4 or higher (best viewed in Full Screen mode)



Large file size, high quality video (19.5MB) (contains English text) - ideal for high-speed Internet connections. Download takes about 60 minutes for 56/k modems or about 3-5 minutes for broadband.

Small file size, less download time (4.34MB) (contains English text) - good for dial-up Internet connections. Download takes about 10-15 minutes for 56/k modems or about 1 minute for broadband.