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by Members for Members

Adding Memory

by Lee Alexander

Have you ever found yourself in a room and wondered why you were there? The cause could be a misfiring axon in your brain. Leaving the room and returning might make the correct connection. In the case of your computer, a warm reboot (Restart) maybe all that is necessary to fix a memory glitch.

As with the meat version, repeated malfunctions are indicative of a deeper problem. A misbehaving SDRAM DIMM (don't you love acronyms?) Synchronous Dynamic Random Access Memory Dual In-Line Memory Module may be at fault. Unlike the organic version, fixing or adding memory in the computer is a relatively easy and inexpensive procedure.

Random Access Memory is the tabula rasa of your computer. Each time you boot up your computer you start with a clean slate. In the first instance, the BIOS (Basic Import/Output System) goes to work and runs a sequence known as POST (Power On Self Test). During this phase the memory modules are tested and any faults detected are announced by beeps from the speaker within the case, not the external speakers.

The next phase is to load the operating system and programs that you have specified in your Start Menu. Programs do not run on the hard disk; all functions are performed in RAM. A shortage of memory space will cause data to be off-loaded to Virtual Memory (aka, the swap file). Frequent writes to the hard drive could indicate a deficiency of RAM.

The physical act of installing more RAM is straightforward. The hard part is selecting the proper type and location, i.e. what slot to put it in. Almost all late-model computers use DDR or DDR2 RAM. The full acronym is DDR SDRAM stands for Double Data Rate Synchronous Dynamic Random Access Memory. Storing data in memory entails turning bits (memory elements such as transistors) on and off, representing 0's and 1's. The speed is regulated by clock cycles, a series of square wave pulses. Initially, the action occurred only on the up tic of the pulse. DDR RAM flips on both the up and down tics of the pulses. The Dynamic designation means the memory must be constantly refreshed. Once upon a time there was RDRAM, manufactured by the Rambus Corp. it had a higher memory bandwidth than SDRAM but was expensive. DDR RAM gave similar performance at a considerably lower price.

Memory Specs

*latencies are memory timings. Access does not happen in a single step. The chips are laid out in rows and columns and are "strobed" to access the memory locations. The numbers refer to the number of clock cycles required. The first number refers to the column address strobe, the next to the delay between the CAS and the RAS (Row Address Strobe), the third is the number of clock cycles needed to close one row and open another, and the last is the number needed to access a specific row of data in RAM. With a higher effective clock speed, slightly longer latencies can actually make for faster memory access.

One of the reasons for the low price of memory today is Microsoft's Vista . Vista benefits from lots of RAM and memory vendors were anticipating a big upbeat in purchases of memory by early adopters of the OS. That did not quite happen; however, the new standard for RAM is 2 GB. You can go higher but beware of older BIOS's. Many will not support beyond 3 or 4 GB.

To see what memory your PC presently has, download the free utility CPU-Z from www.cpuid.org . Be sure to click the tab labeled SPD (serial presence detect). A small chip on the memory module will show rated speeds and latencies.

The two major vendors of memory are Kingston and Crucial. Be sure to visit their web sites where you can specify your PC and get valuable information as to what memory works in your particular machine. Crucial even offers to scan your machine for you.

The following is the result of a search on Kingston.com for my 2002 desktop.

At purchase, the price to upgrade from 128 MB of memory to 512 MB was $130. Kingston 's price (last month) was $50 for a 512 MB module; Crucial's price was $32