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Memory Glossary
FAQ

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Memory FAQ



How can I "max out" the memory on my computer?
You can determine the largest memory module each slot can take by dividing the maximum capacity by the total number of slots. For example, if your computer has a maximum memory capacity of 512MB and has two slots, the largest module you can install in each slot is a 256MB memory module.

However, there are exceptions to this general rule. For example, there are situations where a computer with 4 memory slots and a 2GB maximum memory capacity will accept two 1GB modules. There are also times when a system would only accept a 512MB module at launch, but down the road would take a 1GB module with a BIOS upgrade.

To completely "max out" the memory on your computer, you may need to actually remove memory modules currently installed and replace them with larger-capacity modules. Using the example above, if your computer has one 512MB module already installed, with one memory slot open, you would need to remove the 512MB and install two 1GB modules to truly "max out" your computer.


Do I have to buy the same size upgrade as the memory module currently installed in my computer or can I mix different sizes?
In newer systems using SDRAM or DDR SDRAM memory, you can use modules of different densities with no problem. For example, if your computer came with a 128MB memory module, you can add a 256MB module for a total of 384MB of RAM. However, if you have a "dual-channel" system and want to take advantage of that technology, you will need to ensure that the modules in each memory slot are the same density.


ECC vs. non-ECC — What do I Have and Can I Mix?
When adding new memory, you should match what is already in your system. Adding non-ECC memory to an ECC system will disable the error-checking and correcting ability of your memory modules. While your system may still operate, the enhanced features of the ECC modules will no longer be active in you computer.

You can determine if your system has ECC by simply counting the number of black memory chips on each module. ECC (and parity) memory modules have a chip count divisible by three or five. This extra chip detects if the data was correctly read or written by the memory module. If the data wasn't properly written, the extra chip will correct it in many cases (depending on the type of error). Non-ECC (also called non-parity) modules do not have this error-detecting feature. Any chip count not divisible by three or five indicates a non-parity memory module.

Using ECC decreases your computer's performance by about 2 percent. 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 (non-ECC) memory.


What are the benefits of upgrading your computers memory?
Upgrading your memory is typically the easiest and least expensive way to upgrade your computer for a significant boost in performance. The computer's RAM memory is its workspace, or where all of the instructions it needs to act on are stored temporarily. Think of the RAM as the desk you use to sort through your work. If the size of that desk is small, your efficiency is limited in comparison to a larger desk that allows you to work more effectively and efficiently. Similarly, a computer with more RAM can work more efficiently because it does not need to retrieve information from the hard disk drive as often. 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.


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 physical memory is insufficient, the system uses Hard Disk Space as memory. This is called "Virtual Memory". Since access time of Physical memory is in tens of NanoSeconds and Access time of Hard Disk is in MilliSeconds, the system slows down considerably.


.What's the difference between buffered and unbuffered DIMMs?
High density DIMMs have lots of chips on them and therefore possess a higher capacitive load on the address and control signals in comparison to lower density DIMMs. Some designers use redrive buffers on the DIMM to boost the signals to reduce system loading when compared to the same high density module without buffers. But the buffers introduce a small delay into the electrical signal, so adding buffers to a standard density module would have the effect of slowing down the signal, compared to the same low density module without buffers.


What is Virtual Memory?
This is a method of extending the available physical memory on a computer. In a virtual memory system, the operating system creates a pagefile, or swapfile, and divides memory into units called pages. Recently referenced pages are located in physical memory, or RAM. If a page of memory is not referenced for a while, it is written to the pagefile. This is called "swapping" or "paging out" memory. If that piece of memory is then later referenced by a program, the operating system reads the memory page back from the pagefile into physical memory, also called "swapping" or "paging in" memory. The total amount of memory that is available to programs is the amount of physical memory in the computer in addition to the size of the pagefile.


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.


What's the difference between RDRAM and SDRAM?
RDRAM stands for Rambus Dynamic Random Access Memory. SDRAM stands for Synchronous Dynamic Random Access Memory. The two memories are completely different memory technologies and are not compatible with each other. RDRAM is a unique design developed by a company called Rambus, Inc. RDRAM is extremely fast and uses a narrow, high-bandwidth "channel" to transmit data at speeds much faster than SDRAM.


What is the difference between 72 bit and 64 bit memory?
72 bit memory is commonly known as ECC memory. It has an additional 8 bits for Error Correction Check 64 bit memory is non-ECC. 72 bit or 64 bit configuration are typically found in 168 pin DIMMs.


What should I do with my old memory modules?
We offer a memory Trade-in program that allows you to sell us your old working memory, there is no minimum or maximum quantity. You can trade-in as many as you want. The trade-in memory module do not have to be of the same type as the new ones. (For example, purchase SODIMM Laptop Memory and return SDRAM Desktop memory). We buy most type of computer memory.
For more details on our Memory Trade-In program. For further details about Memory Tradein Program, please visit our trad-in program page at http://www.pacificmemory.com/t-MemoryTradeinDetails.aspx or email us at Tradein@PacificMemory.com.


Memory Trade-in/
Buy-Back Program




We buy Memory. If you are looking to upgrade memory, you can trade-in your old memory towards new memory purchase. Or you can just sell us your old memory and make some extra cash. See details...

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