Questions About the Benefits of Upgrading

What are the benefits of upgrading your computer's memory?
Upgrading your memory is typically the easiest and least expensive way to upgrade your computer for a significant boost in performance. A memory upgrade is particularly helpful for users who work with large files, have more than one program open at one time, or use memory-intensive applications such as games or graphics and video editing software.

What is the optimum amount of memory for the average desktop user?
The type of software applications you're using and the number of programs you open at a time have a direct correlation to how much memory you need on your system. Today's recommended minimum for running most applications is 64MB and, if you are a Windows 2000 or OS X user, 128MB. If you are a gamer or other "power user", you'll probably want 256-512MB. Many people who do intensive graphic design work are happiest with 2GB or more.

Do I need more memory? I hear the hard drive working and my computer is slower.
The reason for the hard drive activity is limited memory. When the memory is full, your system will transfer data to the hard drive. This is called swapping. Since the hard drive is considerably slower than the memory, your system seems slower altogether.

To determine whether you need to upgrade your memory, consider how much memory you currently have and what applications you use. Some programs will use more memory than others and, of course, multitasking will drag the performance down as well.

Will adding more RAM make my Internet browsing faster?
Maybe. Internet browsing speed depends on a huge number of factors, including your connection speed, traffic on the site you're visiting, and the other components in your system. You will probably notice the biggest improvement from additional RAM if are viewing or working with large files (such as photos and digital audio and video) or if you switch between your browser and other applications often.

How do you know it's time for a memory upgrade?
There are several signs indicating it may be time to upgrade your memory. If you see your mouse pointer turn into an hourglass for significant periods of time, if you hear your hard drive working, or if your computer seems to work more slowly than you expect, the reason is probably insufficient memory. When the memory is full, your system transfers data to the hard drive. This is called swapping. Since the hard drive is considerably slower than DRAM, your system seems slower altogether.

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What is CAS Latency?
CAS latency (also referred to as latency) is the amount of time it takes for your memory to respond to a command. Specifically, it is the length of time between memory receiving a command to read data, and the first piece of data being output from memory. Latency is measured in terms of clock cycles and is often noted as CL2 (two clock cycles) or CL3 (three clock cycles).

What is the performance difference between CL2 and CL3?
CL2 parts process data a little quicker than CL3 parts in that you have to wait one less clock cycle for the initial data. However, after the first piece of data is processed, the rest of the data is processed at equal speeds. Latency only affects the initial burst of data. Once data starts flowing, there is no effect. Bear in mind, a clock cycle for a PC100 module is 10 nanoseconds so you probably won't notice a significant performance difference. Most systems will accept either latency part. However, there are some systems that require either CL2 or CL3 parts.

Can I mix CAS2 and CAS3 parts? What should the motherboard settings be?
Yes. CAS2 and CAS3 parts can be mixed. BIOS settings should reflect the CAS3 setting, as the CAS2 module will run at the CAS3 setting when it is installed with a CAS3 module.

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Can I use PC133 or PC100 SDRAM in my 66MHz PC?
Generally, all SDRAM is backward compatible and can run at any bus speed slower than it is rated to run. For example, a PC133 SDRAM DIMM is capable of running at 133MHz, 100MHz, and 66MHz. There are a few older motherboards that require 66MHz SDRAM and that will not accept PC100 or PC133 SDRAM, but they are the exceptions to the rule. Keep in mind that your memory will only operate as fast as the slowest link in your system. If you install PC100 SDRAM in your 66MHz PC, it will only run at 66MHz.

Should I buy a PC100 module or a PC133 module?
If your PC has a 133MHz front side bus (FSB), you will need PC133 SDRAM.

If your PC has a 100MHz FSB, you can use PC100 or PC133 SDRAM. All PCs that accept PC100 SDRAM will also accept PC133 SDRAM; however, your memory will only run as fast as the slowest "link" in your system. If you have a 100MHz FSB or any PC100 modules installed, any PC133 modules that you install will only operate at 100MHz.

PC133 SDRAM doesn't offer any immediate benefit over PC100 SDRAM if you have a 100MHz FSB. However, if you are planning to upgrade to a system with a 133MHz FSB in the future, you may be able to use the PC133 modules you purchase now in your future system.

Can I mix and match PC100 and PC133 parts?
Generally you can mix PC100 and PC133 memory in the same system. The faster memory will run at the slower memory's speed (in this case PC100). However, there are some systems that will not correctly run this memory configuration. It is rare, but we suggest you contact your computer manufacturer or motherboard manual for specifics.

Why won't my motherboard accept 133MHz memory at a bus speed of 133?
There are several different bus settings in your motherboard's BIOS. Consult your motherboard manual to see if the proper settings are enabled and that the front side bus (FSB) is set correctly. You may also need to check the motherboard manufacturer's Web site to see if your board has the latest BIOS revision.

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How do I know if I need parity, non-parity, or ECC memory?
The general rule of thumb in deciding what type of memory you need is to look at what's already installed in your system. To find out if you have ECC, parity, or non-parity memory, count the number of chips on the module. Divide the total number of chips by three. If you can evenly divide the number of chips by three, the module is ECC or parity, if not, then it is a non-parity module.

So if your system does have ECC or parity memory (the chips are evenly divisible by three), how do you know which one you have? One way is to look at the part numbers on the chips of your module. If each chip has the same part number, you have ECC. If one chip is different, you have parity.

If you are building a PC and plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity.

Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.

What is the difference between ECC and non-parity memory? Is there a performance difference?
ECC (error checking and correcting) memory performs "double bit detection and single bit correction." This means that if you have a single bit memory error, the chipset and memory will find and repair the error on the fly without you knowing that it happened. If you have a double bit memory error, it will detect and report it. Non-parity memory, on the other hand, has no error detection and correction capabilities.

Using ECC decreases your PC's performance by about 2%. Current technology DRAM is very stable and memory errors are rare, so unless you have a need for ECC, you are better served with non-parity SDRAM.

If you already have a PC, you need to match the type of memory already installed in your system. If you are unsure whether you have ECC or non-parity, count the number of small, black, IC chips mounted on one of your existing DIMMs. If the number of chips is evenly divisible by three, then you need ECC. If the number of chips is NOT evenly divisible by three, you have non-parity memory.

If you are building a PC and plan to use your system as a server or a similar mission critical type machine, it is to your advantage to use ECC. If you plan to use your PC for regular home, office, or gaming applications, you are better off with non-parity.

Can you mix and match parity (or ECC) and non-parity modules?
No. When adding new memory, you need to match what is already in your system. Parity modules have an extra chip that detects if data was correctly read or written by the memory module, depending on the type of error. However, a parity module will not correct the error. ECC modules can detect double bit errors and correct single bit errors.

You can determine if your system has parity by simply counting the number of black memory chips on each module. Parity and ECC memory modules have a chip count divisible by 3. Any chip count not divisible by 3 indicates a non-parity memory module.

Can I use memory with ECC on a board that does not support ECC?
Most motherboards that do not have an ECC function within the BIOS are still able to use a module with ECC, but the module will run in non-ECC mode. Keep in mind, there are some cases where the motherboard will not accept an ECC module, depending on the BIOS programming. The only sure-fire way to test this is to place the module in the motherboard and see if the BIOS will recognize the memory addition.

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After adding memory I got the error message, "Invalid system disk. Replace disk and press any key," and my system won't boot. Why?
This error message is consistent with a couple of problems. The most common is that when reaching to install your memory, you accidentally bumped a cable (perhaps a hard drive cable). The first thing we suggest is to reseat all the cables in your computer, including the cables to the hard drive and hard drive power.

The second and much simpler solution may be that you have a floppy disk (that is not a boot disk) in your floppy drive. Please check to see that there are no disks in your floppy drives.

Does it matter which slots I plug my new module in?
In general, you will get the best performance if you put the largest module (in megabytes) in the lowest-numbered slot. For example, if your computer comes with 32MB of removable memory and you want to add 128MB, it would be best to put the 128MB module into slot 0 and the 32MB module into slot 1.

I have more than 512MB RAM. Why does Windows say I'm out of memory?
If you have more than 512MB RAM and are running Windows 95, 98, 98SE, or ME, you may not have enough cache to handle all of your memory. Solutions to this problem can be found at Microsoft's Web site.

Will buffered and unbuffered DIMMs fit into the same socket?
The two different types of modules (buffered/unbuffered) are not interchangeable and even use slightly different printed circuit boards (PCBs). If you try to install the wrong type, the first notch on the bottom of the module will be offset.

You can determine if the module is buffered by looking at the leads next to the first notch. If the leads are evenly spaced, the module is buffered. If the leads are not evenly spaced (a larger PCB area next to the lead) the module is unbuffered.

Buffered EDO and FPM DIMMs have a buffer logic chip that is used to distribute the load placed on the chipset and is primarily used only in servers on PC platforms. Apple computers have used primarily buffered modules until their recent G3 and G4 series computers.

Is it difficult to install additional memory?
Memory is the easiest of all system upgrades. Installing more memory usually involves simply removing the system cover and inserting the new modules into the empty memory slots. Then, replace the cover and power up the system. Most systems will recognize the increased memory automatically.

My new DIMM slides into the slot but the retaining clips don't lock. Why?
There are two things to keep in mind when installing DIMMs.

1. 1. The notches on the bottom of the memory module (where the gold leads are) should line up with the memory slot.
2. 2. Each memory slot in your computer will have retaining clips on either side. As you push down on the memory module, these clips will automatically move up and lock into place. If you have to manually move the clips into place, then you are not pushing down hard enough on the memory module. 20 to 30 pounds of pressure is typical.

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Is my memory the same thing as my hard drive?
If you haven't worked with computer hardware before, it can be easy to confuse your hard drive with memory. However, your hard drive is not the same thing as memory (also called RAM). You can think of your hard drive as being like a filing cabinet. It's a good place to store a lot of information for a long time. Your RAM (or memory) is kind of like the top of your desk. This is where your system stores the information you're currently working on.

RAM is about 100 times faster than your hard drive. However, your hard drive can store information after the power is turned off, while RAM cannot. Your system needs both memory and a hard drive to operate properly.

Can I mix and match modules of different sizes (e.g., 64MB modules and 128MB modules)?
Yes. Different sizes of SDRAM modules can be mixed together. In other words, you can use 32MB, 64MB, 128MB, and 256MB modules together. Keep in mind, the largest module should always be placed in the first slot for best performance.

The exception to this rule is systems that require memory to be installed in banks of two or more. For example, some systems require modules to be installed in banks of two. In this case, the two modules in each bank need to be the same size. If your system had two banks of two (four total slots), you could install two 32MB modules in bank 0 and two 64 MB modules in bank 1. Your total memory would be 192MB.

Check your system documentation to see if your computer requires memory to be installed in banks of two or more.

What does "registered" SDRAM mean?
The term "registered" refers to how the memory module processes signals. Registered modules contain a register that delays all information transferred to the module by one clock cycle. This type of memory is primarily used in servers and was designed for modules with 32 or more chips on them to help ensure that data is properly handled.

While most PCs will only accept unbuffered SDRAM, there are some that accept registered SDRAM. Keep in mind that when you install registered SDRAM, all of the modules installed in your PC must be registered because unbuffered and registered modules are not interchangeable.