Windows number of memory modules

Immediately press the F10 key if your computer was built in or later came with Windows Vista or Windows 7. Immediately press the F1 key if your computer was built before Windows XP or earlier. 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 of banks is equal to the number of memory slots on the motherboard. The number next to each memory bank is the amount of memory for the module that is installed in that bank.

If no amount is listed, that memory slot bank is empty. Installing memory in your desktop computer Use the following steps to install memory in an HP or Compaq desktop computer. After reviewing the following steps, if you are not confident in performing the installation yourself, contact an HP authorized distributor for technical assistance. The customer assumes all risk and liability for damages for any such installation or upgrade. You might find that your HP or Compaq computer is able to support a physical installation of 4 GB or more memory.

However, this maximum memory might be further limited by the operating system not being able to address the full range of physical memory. This limitation is present on all bit hardware and bit operating systems and is not limited to HP and Compaq PC systems or Microsoft software operating systems. See Maximum memory supported by operating system for more information.

Step 1: Opening the access panel to install memory in your desktop computer Use the following steps to open the case:. Be careful not to slide skin along any interior metal edge of the computer. To reduce the chance of ESD damage, work over a non-carpeted floor, use a static dissipative work surface such as a conductive foam pad , and wear an ESD wrist strap connected to a grounded surface.

In the Search field or Questions or keywords field at the top of this page, type your computer model number, a space, and the words "opening the case. 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. 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, type your computer model number , a space, and the words " opening the case. Step 2: Determine if memory needs to be removed before installing additional memory in your desktop computer 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 degree angle.

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

If the computer does not have an empty socket, skip to the next step 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 3: Remove a memory or continuity module in your desktop computer 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 of the socket. Step 4: Add a memory module in your desktop computer Use the following steps to insert a memory module into an empty socket:.

Align the slots in the memory module to the notches in the memory socket. 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 5: Replace the cover after installing memory in your desktop computer 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. If the computer does not start or a beep code sounds, use the next section to troubleshoot the problem.

If the computer starts, make sure that the new memory amount displays in the BIOS as is shown in the section Verify how much memory can be added. What to do if problems occur after installing memory If the computer does not start properly after replacing the memory the screen will remain black and the computer will turn itself off within a few seconds , or if there are memory errors including beeps after the computer starts, try the following steps:.

Reseat the new memory module by following the steps in the Installing memory section. 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 cable 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 Finding memory information for your computer model and Verifying how much memory can be added.

You can remove and reference from the memory module that originally came installed in the computer. One difference between this analogy and the way things really work in a computer is that when a file is loaded into memory, it is a copy of the file that is actually loaded; the original still resides on the hard disk. Because of the temporary nature of memory, any files that have been changed after being loaded into memory must then be saved back to the hard disk before the system is powered off which erases the memory.

If the changed file in memory is not saved, the original copy of the file on the hard disk remains unaltered. This is like saying that any changes made to files left on the desktop are discarded when the office is closed, although the original files are still preserved in the cabinet. Memory temporarily stores programs when they are running, along with the data being used by those programs.

RAM chips are sometimes termed volatile storage because when you turn off your computer or an electrical outage occurs, whatever is stored in RAM is lost unless you saved it to your hard drive. Because of the volatile nature of RAM, many computer users make it a habit to save their work frequently—a habit I recommend. Many software applications perform periodic saves automatically in order to minimize the potential for data loss.

Physically, the main memory in a system is a collection of chips or modules containing chips that are usually plugged into the motherboard. These chips or modules vary in their electrical and physical designs and must be compatible with the system into which they are being installed to function properly. This chapter discusses the various types of chips and modules that can be installed in different systems. To better understand physical memory in a system, you should understand what types of memory are found in a typical PC and what the role of each type is.

Three main types of physical memory are used in modern PCs. Remember, I'm talking about the type of memory chip, not the type of module that memory is stored on.

The only type of memory you normally need to purchase and install in a system is DRAM. The other types are built in to the motherboard ROM , processor SRAM , and other components such as the video card, hard drives, and so on.

Read-only memory, or ROM, is a type of memory that can permanently or semipermanently store data. It is called read-only because it is either impossible or difficult to write to. ROM also is often referred to as nonvolatile memory because any data stored in ROM remains there, even if the power is turned off. As such, ROM is an ideal place to put the PC's startup instructions—that is, the software that boots the system.

Both are simply types of memory. In other words, a portion of the system's random access memory address space is mapped into one or more ROM chips. This is necessary to contain the software that enables the PC to boot up; otherwise, the processor would have no program in memory to execute when it was powered on.

ROMs on adapter cards contain auxiliary BIOS routines and drivers needed by the particular card, especially for those cards that must be active early in the boot process, such as video cards. Cards that don't need drivers active at boot time typically don't have a ROM because those drivers can be loaded from the hard disk later in the boot process.

Flash is a truly nonvolatile memory that is rewritable, enabling users to easily update the ROM or firmware in their motherboards or any other components video cards, SCSI cards, peripherals, and so on.

The main advantages of DRAM are that it is very dense, meaning you can pack a lot of bits into a very small chip, and it is inexpensive, which makes purchasing large amounts of memory affordable. The memory cells in a DRAM chip are tiny capacitors that retain a charge to indicate a bit.

The problem with DRAM is that it is dynamic—that is, its contents can be changed. With every keystroke or every mouse swipe, the contents of RAM change. And the entire contents of RAM can be wiped out by a system crash. Also, because of the design, it must be constantly refreshed; otherwise, the electrical charges in the individual memory capacitors will drain and the data will be lost. Refresh occurs when the system memory controller takes a tiny break and accesses all the rows of data in the memory chips.

The standard refresh time is 15ms milliseconds , which means that every 15ms, all the rows in the memory are automatically read to refresh the data. Refreshing the memory unfortunately takes processor time away from other tasks because each refresh cycle takes several CPU cycles to complete. The time between refresh cycles is known as tREF and is expressed not in milliseconds, but in clock cycles see Figure 6.

Figure 6. It's important to be aware that increasing the time between refresh cycles tREF to speed up your system can allow some of the memory cells to begin draining prematurely, which can cause random soft memory errors to appear. A soft error is a data error that is not caused by a defective chip. To avoid soft errors, it is usually safer to stick with the recommended or default refresh timing. It is almost always best to use default or automatic settings for any memory timings in the BIOS Setup.

Many modern systems don't allow changes to memory timings and are permanently set to automatic settings. On an automatic setting, the motherboard reads the timing parameters out of the serial presence detect SPD ROM found on the memory module and sets the cycling speeds to match.

DRAMs use only one transistor and capacitor pair per bit, which makes them very dense, offering more memory capacity per chip than other types of memory.

Currently, DRAM chips are being prepared for production with densities up to 4Gb MB per chip, which at one transistor per bit requires at least 4 billion transistors. The transistor count in memory chips is much higher than in processors, because in a memory chip the transistors and capacitors are all consistently arranged in a normally square grid of simple repetitive structures, unlike processors, which are much more complex circuits of different structures and elements interconnected in a highly irregular fashion.

The transistor for each DRAM bit cell reads the charge state of the adjacent capacitor. If the capacitor is charged, the cell is read to contain a 1; no charge indicates a 0. The charge in the tiny capacitors is constantly draining, which is why the memory must be refreshed constantly. Even a momentary power interruption, or anything that interferes with the refresh cycles, can cause a DRAM memory cell to lose the charge and thus the data. If this happens in a running system, it can lead to blue screens, global protection faults, corrupted files, and any number of system crashes.

DRAM is used in PC systems because it is inexpensive and the chips can be densely packed, so a lot of memory capacity can fit in a small space. Unfortunately, DRAM is also relatively slow, typically much slower than the processor. For this reason, many types of DRAM architectures have been developed to improve performance.

These architectures are covered later in the chapter. Another distinctly different type of memory exists that is significantly faster than most types of DRAM. SRAM memory is available in access times of 0.

This is because of the SRAM design, which calls for a cluster of six transistors for each bit of storage. The use of transistors but no capacitors means that refresh rates are not necessary because there are no capacitors to lose their charges over time.

As long as there is power, SRAM remembers what is stored. With these attributes, why don't we use SRAM for all system memory? The answers are simple. The lower density means that SRAM chips are physically larger and store fewer bits overall. The high number of transistors and the clustered design mean that SRAM chips are both physically larger and much more expensive to produce than DRAM chips. The SRAM cache runs at speeds close to or even equal to the processor and is the memory from which the processor usually directly reads from and writes to.

During read operations, the data in the high-speed cache memory is resupplied from the lower-speed main memory or DRAM in advance. To convert access time in nanoseconds to MHz, use the following formula:. Up until processors were running at speeds of 16MHz, the available DRAM could fully keep pace with the processor and motherboard, meaning that there was no need for cache.

This occurred way back in and with the debut of systems with the processor running at speeds of 16MHz to 20MHz or faster. These were among the first PC systems to employ what's called cache memory , a high-speed buffer made up of SRAM that directly feeds the processor. Because the cache can run at the speed of the processor, it acts as a buffer between the processor and the slower DRAM in the system.

The cache controller anticipates the processor's memory needs and preloads the high-speed cache memory with data. Then, as the processor calls for a memory address, the data can be retrieved from the high-speed cache rather than the much lower-speed main memory. Cache effectiveness can be expressed by a hit ratio.

This is the ratio of cache hits to total memory accesses. To find out whether your motherboard is compatible with the new memory run. Like Liked by 1 person. Like Like. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email.

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