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Adding more memory to a computer is a very easy way to get nice performances enhancements. How much memory is required to make your computer run efficiently is depending of many factors. Among these factors, the programs and applications you're using are of first importance. Some applications run very well on systems with 32MB of memory while some others are much more demanding. Graphic and video programs are often requiring more than 32MB of memory to run efficiently. On the other hand, if you happen to run many applications simultaneously you might get frequent uses of the hard-disk swap file which is decreasing your system performances. To reduce you HDD swap file access and get better performances you need to add more memory. Here are the results of a research conducted by Ziff Davis about how much performance gain could be expected by a system when adding more memory;
A quick look at these graphics let us see that the higher the CPU frequency the better the performances gain are. This may not be true in all cases but it's a very interesting observation! Installing additional memory to modern computers is quite easy but there are many different types of memory: 3-volt, 5-volt, SIMMs, E-SIMMs,D-SIMMs, etc. Memory is usually "packaged" as SIMMs or DIMMs. SIMMs, or Single In-Line Memory Modules. This type of memory modules uses tabs on both side of the printed circuit board to conduct the same signal. DIMMs, or Dual In-Line Memory Modules. This type of memory modules uses tabs on both sides of the printed circuit board but with different signals. Usually to add more memory you simply turn off your computer, plug in the memory module (as described at the bottom section of this page), turn on the computer, and if your computer BIOS can determine the newly added memory and reconfigure itself you have nothing more to do, otherwise, you will have to go to your BIOS setup and manually make the changes. Before to install more memory you must make sure of the memory types supported by your system and the following information will be required;
You will also have to choose what type of memory to install so carefully read your motherboard manual to see what types of memory are supported. Memory modules actually come in three format, 30-pin, 72-pin, and 168-pin and most computers built nowadays use both 72 and 168-pins memory modules. Many computers are requiring that the memory modules be installed in pairs. For instance, to install 32MB of memory you may not be allowed to use only a single 32MB memory module and you could be forced to install two 16MB memory modules as it is the case on most of the Pentium motherboard. Computer motherboard only support a maximum given amount of memory. While some computer cannot go over 256MB of memory some others can accept up to 1GB and even more so refer to your computer manual listing the various combinations of memory modules that your computer support. The amount of cache memory installed on your computer motherboard must also be taken very seriously. Many motherboard only have 256k of cache memory installed and this is just enough to cache 16MB of main memory so if you choose to add more main memory you could actually slow down your system performances because the additional memory wont be cached. To efficiently use 32MB of main memory you need to have a cache size of at least 512k installed. The motherboard Chipset is also concerned about the maximum cachable area because some Chipset (Intel 430TX cannot cache more than 64megs of memory) are not capable to cache more than a given amount of memory so before to add more memory you must make sure that the Chipset used on your motherboard can effectively cache all the main memory installed on your motherboard because uncached memory can slow down you computer performances by as much as 20% ! Computer memory speed is measured by the number of megabytes of data it can be read from or writen to in a period of one second while memory is sold by its timing frequency speed specified in nanoseconds (ns). Most of the peoples think that the lower the number of nanoseconds, the faster the memory and its not false but not completely true because when you compare memory chips of the same timing (i.e. EDO Dram of 60ns) you can measure very noticeable transfer rates differences from brand to brand so it'll be much wiser to buy memory for its real meg./sec. data bandwidth performances instead of its timing in nanoseconds! Your motherboard user manual will tell you which types of memory modules your computer support and the timing frequency that the memory chips must be. If the timing of the module is too slow, the computer may slow down in order to wait for the memory while if the memory timing is too fast, then it's the memory that is waiting. Finally, you can choose between gold plated or tin plated connectors for your memory modules. The only difference between these types of modules is that gold plated connectors memory modules do not corrode and tend to be more expensive. A good rule of thumb is to always match the metal type of the memory connectors with the metal type of the memory socket connectors to avoid corrosion. Gold plated socket connectors wouldn't do a good job in a long term period if used with tin plated memory connectors because it would favorise the corrosion as it always happen when two different types of metal are used in the same environment so you should allay use the same type of metal for both your memory modules connectors and the memory socket connectors installed on your motherboard.
Parity and Non-Parity The main difference between parity and non-parity memory is that the parity memory has the ability to detect single-bit errors and halt the system while non-parity memory provides no error detection.
Error Checking and Correcting (ECC) The ECC memory is a more advanced memory that can automatically detect and correct single-bit error without halting the system. In can also halt the system when more than one error is detected. However, the ECC memory is requiring more overhead to store data than parity memory therefore causing some performance degradation in the memory subsystem.
Dynamic Random Access (Dram) DRAM is a type of memory that requires to be constantly refreshed to keep the charges that hold the data alive. This "refreshing" is the main cause of the delays between access. This type of memory can be considered as obsolete.
Fast Page Mode Dram (FPM) Dram The Fast-page memory is similar to DRAM memory but it allows for successive memory accesses with minimized delays between access. Typical access is clocked at 5-3-3-3for a maximum bandwidth of 100MB/sec in a 32-bit system and 200MB/sec for a 64-bit system. This type of memory can also be considered as obsolete.
Extended-Data Output (EDO) Dram EDO DRAM also named hyper-page mode DRAM allows memory cycle times to be shortened by condensing the CAS timing to get more data out in a given access sequence. In CPU cycles this gives 5-2-2-2. Computer performances increase are to be gained by the use of this memory because EDO DRAM memory is about 15% faster than FPM DRAM memory. The maximum data transfer rate (bandwidth) of EDO DRAM is about 264meg/sec. This type of memory will almost be considered as obsolete by the end of 1998.
Burst EDO (BEDO) Dram BEDO incorporates some burst mode features into EDO DRAM to further increase performances. BEDO RAM reads data in a burst, which means that when the address has been provided, the next three access are performed in only one clock cycle each, so, the data is read in a 5-1-1-1 burst. This type of memory is more a transition between the EDO DRAM memory and the SDRAM memory and it has never been clear that BEDO DRAM will be on the market for a long period of time.
Synchronous DRAM (SDRAM) SDRAM is different from ordinary DRAM by the use of a synchronous interface. In standard DRAM memory an address is recognized only when RAS or CAS lines are enabled while in SDRAM memory addresses are latched on clock transitions which gives a good enhancement for the data transfers rates. Because SDRAM generates sequential addresses internally it use burst mode to outputs data from consecutive row locations as well as a pipeline to allow random accesses on a row on each of the clock cycles. SDRAM is accessed at 5-1-1-1 making it as fast as BEDO RAM but it can handle bus speeds in excess of 100 MHz. The maximum data transfer rate (bandwidth) of SDRAM memory is about 528meg/sec.
DDR SDRAM (also called SDRAM II) DDR DRAM is a variance of the SDRAM memory. The main difference between SDRAM and DDR SDRAM is that the DDR SDRAM has the ability to use both the raising and falling edges of the clock to transfer data which is effectively doubling its data output performances. DDR SDRAM maximum transfer rate (bandwidth) is in excess of 1gig/sec.
Rambus DRAM (RDRAM) RDRAM is a whole new concept using a new chip package with a low-pin-count, high-speed, synchronous architecture. Because every aspects of its internal structure like trace length, pin capacitance, voltage swing has been rigorously redefined this type of memory is able to offer very high performances. This memory is accessed on both the raising and falling edges of the clock. A single channel RAMBUS memory module deliver performances about 3 times higher than SDRAM 64-bits 100mhz memory modules. For instance a single channel RDRAM memory system has a data bandwidth of 1.6 GByte/sec. The main advantage with Rambus is that controllers can be designed to use 2 Rambus channels (and even 4 channels!) in parallel, yielding a total of 3.2 GByte/sec bandwidth while a 4 channel RAMBUS memory system. can go as high than 6.4 GByte/sec!
As i said before, installing memory modules is quite easy and with the help of the following pictures it's going to be a kid game for everyone of you.
Below, you can see the photography of a 30 pins Simm memory module:
As you can notice a notch is present on the bottom left side of the module so you align this notch to correspond with the memory socket and push it to the bottom of the socket. You cant make mistakes because you wont be able to insert the module on the wrong side. So you just align this notch to correspond with the memory socket and push it to the bottom of the socket and then you snap the latch on both sides of the memory module Installing Simm's memory modules Here is a photography of a 72 pins Simm memory module:
Again, on this type of memory module a notch is present on the bottom left side so you just align this notch to correspond with the memory socket and push it to the bottom of the socket and then you snap the latch on both sides of the memory module. You cant make mistakes because you wont be able to insert the module on the wrong side. Installing Dimm's memory modules Here is a photography of a168 pins Dimm memory module:
The Dimm memory modules is somewhat different of the Simm module as its notch are placed differently. Instead of a corner notch there is an off center notch as well as a center notch, so, the way this memory module is manufactured only allow to be inserted in its socket in only one position therefore avoiding any possible mistakes. Again, after the memory modules is inserted you must snap the latch on both sides of the memory module. |
