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Frequently Asked Memory Questions

What is an EEProm? An EEprom is a tiny chip (electrically programmable read only memory device) on the end of the memory module that gives the motherboard information about how the memory module is built and how the memory module needs to be read.
What is "module configuration" A memory module is basically DRAM chips soldered to a circuit board . Together the DRAM chips hold the memory information and the circuit board is the highway that routs the information. The "module configuration" is the design of both what quantity / arrangement and type of chips the memory module uses to achieve the specified capacity as well as in what arrangement and order these chips hold and send the memory information to the motherboard. Different motherboards are able to understand different configurations, but no motherboard is able to understand all configurations.
What is "RAM"? RAM
random access memory
When you run an application like Microsoft Word, the program is called up from its permanent storage area (like the hard drive, floppy disk, or CD-ROM) and moved into the RAM, where it sends requests to the CPU. Using the faster PC100 memory preferred by 350-, 400-, and 450-MHz Pentium II processors means your information spends less time in line before being processed. (PC100 chips are rated to perform at bus speeds up to 100 MHz.) Your computer should have as much RAM as you can afford so it can work efficiently. It also pays to have lots of memory in your system because some operating systems, including Windows 95 and 98, swap applications from memory to your hard drive when the RAM gets filled. That means that instead of having your speedy RAM sending out requests, the OS sends the work to be done by the much slower hard drive.
What is a "Simm"? A simm is a " single inline memory module" typically running at 60 or 70ns. Used in old computer of the early Pentuim to P200. They came in 30 or 72 pin varieties.
What is "EDO RAM"? extended data-out RAM
This form of dynamic RAM speeds access to memory locations by working on a simple assumption: the next time memory is accessed, it will be at a contiguous address in a contiguous chunk of hardware. This assumption speeds up memory access times by up to 10 percent over standard DRAM.
What is "DRAM"? dynamic RAM
DRAM is the working man of readable/writable memory: it's not the best, but it's cheap, does the job, and is available almost everywhere you look. DRAM data resides in a cell made of a capacitor and a transistor. The capacitor tends to lose data unless it's recharged every couple of milliseconds, and this recharging tends to slow down the performance of DRAM compared to speedier RAM types.
What is "SDRAM" synchronous dynamic RAM
Sending data from main memory to the system processor is consistently one of the biggest performance bottlenecks in any PC. Even the fastest standard DRAM and EDO memory cannot keep up with the 66-MHz bus speeds used on many Pentium systems. SDRAM incorporates new features that allow it to keep pace with bus speeds as high as 100 MHz. It does this primarily by allowing two sets of memory addresses to be opened simultaneously. Data can then be retrieved alternately from each set, eliminating the delays that normally occur when one bank of addresses must be shut down and another prepared for reading during each request.

What is a "DDR MEMORY" DDR Memory is a new type of SDRAM that is able to double the read / write speed of the previous generation of SDRAM memory. There are currently 2 speeds offered - 200MHz (Called PC1600 - because it is able to transfer 1600Mbit / sec) and the newer 266MHz (Called PC2100 - because it is able to transfer 2100Mbit / sec). These DIMMs are 184 Pin in size and are not interchangeable with older SDRAM modules. DDR memory can only be used in systems designed specifically for DDR memory
What is a "Cas Latency" In an SDRAM Module there are different operations that need to occur a different times within the clock cycle. The "Cas Latency" rating of a memory module is a minimum amount of time that module needs to wait before it can continue to the next section of the read / write cycle. The larger the number the longer the module needs to wait before it can proceed to the next section of the cycle, thus often making it harder for the module to be ready in time for the next section of the cycle.
What is module noise and how will it effect my system? The green memory module board routs information from the black DRAM chips to the gold pins on the edge of the module via a system of pathways called "traces". The better that you are able to isolate these traces and make the path unobstructed and the proper length, the better the integrity of the memory signal will be. Noise occurs when there is a cross talk of information between these traces or when the path of the trace is not clear. This noise can either slow the system as it has to repeat the same instruction, or it can corrupt the information causing errors and crashes.
Will PC133 work in my PC100 system? Maybe, if the EEprom settings and module configuration of the PC133 module properly match the requirements of your system motherboard then the PC133 module should be able to be run at 100MHz.on your PC100 system.
Why do some modules work in AMD Athlon systems and others don't? CPU manufacturers seem to have put forth little information about memory compatibility, however based on what we have seen, in addition to normal compatibility issues, Athlon systems are more sensitive to noise and the quality of the module. For a few years higher quality memory module manufacturers have been advertising that if you use lower quality parts the high speed of SDRAM will cause data errors because of lower quality of design & components used. Because of the amplification of the signal that occurs inside the very high speed CPUs (& 200MHz processor bus) this higher level of signal errors present in lower cost modules seem to be significant enough to cause the systems to be unstable. We have also started to see this same issue appear in the new high speed Pentium III CPUs .
If I plan on overclocking my system what type of memory should I use? Overclocking the system forces the memory to shorten the internal delays and force timings even faster than a system running normally at the higher bus and system speed. They recommend the lower cas latency / lower noise parts availablel. Some people report systems perform overclocking better with high quality PC166 / PC150 memory, rather than PC100 / PC133.