More RAM, More Power Adding more memory to your system is the best money you can spend on a system upgrade because you get the most bang for the buck. If you own a computer that's a few years old and not exactly considered a power house anymore, but your budget is tight and you don't have the cash to spring for an entire new system, you definitely want to look into adding more RAM. No, it won't quadruple the speed of your processor, but it will give you a noticeable increase in performance. Why? Applications these days need more and more memory to run efficiently. If your system has only 16 or 32MB of memory, Windows needs to utilize virtual memory. This is a chunk of hard drive space that is being used to simulate memory. Windows will try to keep applications that are currently being used in real memory and move other applications into virtual memory. This process is called swapping, hence the name swapfile for the disk space used as virtual memory. The problem is that if you have a few programs open Windows will have to do a lot of swapping. But there is a big performance difference between real memory and virtual memory. Real memory can be accessed much faster than the disk drive, especially if you have an older drive that doesn't support faster transfer rates like ATA-66 or ATA-100, and/or has a slow spindle speed like 5400RPM or less. When you add more memory, Windows can keep more applications and processes in real RAM and access them much faster, which leads to an overall performance increase. How Much Is Enough? Since applications, operating systems, and their system requirements grow at a steady pace, there is really no definite answer to this question. But here are a few guidelines that will help you decide what's the optimal amount of RAM for your machine: Windows 9x/ME - The sweet spot for Windows 9x is 128MB. If you upgrade from 16 or 32MB to 128MB, you'll get your money's worth. But upgrading to more than 128MB will yield only a marginal performance increase Windows NT/2000 - Windows NT and Windows 2000 address memory differently than Windows 9x/ME and take much better advantage of higher amounts of memory - the more RAM you throw at it, the merrier. To get decent performance out of NT/Win2K, you should have at least 128MB, preferably 256MB Remember that memory is cheap (at least right now), so be generous. Memory would be the wrong place to cut corners. To find out what OS and how much RAM you currently have, go to Start / Settings / Control Panel / System / General. The amount of memory will be indicated in KiloBytes (KB), so you'll need to divide that number by 1024 to get the amount of MegaBytes (MB) since one MB equals 1024 KB. Memory vs. Resources If you're running Windows 9x/ME you might run into problems with low system resources. Don't confuse this with low memory, those are two different items, and upgrading your memory will not help resolve resource issues. For more info on system resources refer to our article about Managing Windows Resources - http://www.pcnineoneone.com/howto/resources1.html. What Type Of Memory? Now that you have an idea how much memory you want to get, you'll need to do a little bit of research to make sure that you get exactly the type of memory that works with your motherboard. This is extremely important for several reasons: - Some motherboards are very specific about the type of memory. This is especially true for some name-brand machines like Compaq, Dell, Gateway, etc. A lot of times they don't work with generic memory. - Each memory slot usually has a limit regarding the size of the memory module installed. You don't want to buy a 256MB module just to find out that the motherboard only supports up to 128MB per slot. However, such a limitation can usually be corrected with a BIOS upgrade. - Compatibility is an issue when you plan to mix and match the new RAM with the existing modules. Sometimes they don't play nice unless they match. Consult your system documentation or the vendor to find out exactly what type of memory is currently in your machine. If it's a Pentium II or newer machine, most likely it uses 168-pin DIMMs. If it's a first generation Pentium or older machine, it probably uses 72-pin SIMMs. Be sure to dig up a copy of the motherboard manual so you can read up on the exact memory requirements. This is important because you need to know if the motherboard has any special requirements or limitations as mentioned above. If you don't have the original paper copy of the manual, chances are that you can download it from the manufacturer's web site. Adding Or Replacing? You can go one of two routes: Adding memory - If your existing memory is good, then you might want to consider just adding an additional stick. For example, you might have currently 64MB of PC-100 SDRAM, and want to add another stick of 64MB PC-100 SDRAM to make it 128MB total. Nothing wrong with that. The only caveat here is that you should make sure that the additional memory can coexist peacefully with your existing RAM. Replacing memory - If your existing memory is old or slow or minuscule, you might want to consider trashing it and replacing it with a completely new set. Mix'n'Match If you're planning to add more RAM to your existing setup, you need to make sure that they will work together. Here are a few things to be aware of: - SIMMs are harder to match up. For example, you generally can't mix a pair of Fast Page Mode (FPM) SIMMs with a pair of EDO SIMMs, although some boards will support mixing different types. Under no circumstances, however, can you mix types within a bank. You also need to pay attention to the speed. If your system has 60 nano-second (ns) access time SIMMs installed, and you add a pair of 70ns SIMMs you could run into trouble if your system needs at least 60 ns. Be sure to get at least the same speed or faster. Consult your system documentation to be sure. If your system accepts the mixed speed modules, the speed they will run at will be the lowest common denominator, e.g. if you mix 60ns with 70ns SIMMs, they will run at the slower 70ns. Also pay attention to the order. Install the newer and bigger pair into the first bank (bank 0) and move the older pair to the second bank (bank 1). - DIMMs are easier to match up. For example, you might have a stick of 64MB PC-100 Non-ECC RAM and add a stick of 64MB PC-133 ECC RAM. They normally work together, but please be aware that they will run at the lowest common denominator, in this case PC-100 Non-ECC mode. DIMMs are usually labeled with the bus speed they're guaranteed to run at. PC- 66, the first generation DIMMs, were made to run at a front side bus (FSB) speed of 66 MHz, because the processors they were used for (older Pentium II and Celeron) ran with a 66 MHz FSB. PC-100 means the DIMM can run fine with a FSB up to 100 MHz (or lower, they are backwards compatible). PC-133 means the DIMM can run fine with a FSB up to 133 MHz (or lower, they are backwards compatible). But the other way around you'll run into problems when trying to run a PC-100 DIMM on a 133 MHz FSB. Then there is CAS (Column Address Strobe) Latency - short: CL. It describes the amount of clock cycles you have to wait for initial data access on the actual memory chip. The lower the latency, the faster the access. Therefore CL 2 would be faster than CL 3. However, since three clock cycles wait translates to about 24 nanosecond (ns) wait, compared to 16 ns wait with a CL 2 rating (assuming a speed of 8 ns), we're talking a difference of 8 ns - a difference that is negligible for the average user. CAS Latency is more important when you start pushing the limits of a machine, e.g. when overclocking. Otherwise it's probably not worth spending the extra money. The main thing to remember with CL is that your memory can only run at the lowest common denominator, so if you have a DIMM rated as CL 2 and a DIMM rated as CL 3, they will both run at CL 3. Where To Buy Depending on what you're looking for, you have several options. If you want a piece of cheap, generic memory and are confident that it will work fine in your machine, then your best bet is probably to go to our Best Prices page - http://pcnineoneone.pricegrabber.com/ - use the filter option on the right to narrow it down by RAM size, type, and speed, and find the best prices online. If you prefer to get quality brand-name memory for a decent price, and/or need some help finding the right memory that's guaranteed to work with your system, you should check out Crucial Technology's web site - http://www.crucial.com. They offer good quality Micron memory at a good price. Search by memory type to find the standard RAM you want to get. Another great feature on their site is the memory selector to make sure you get memory that is guaranteed to work with your PC. If you have a brand-name PC that requires a very specific type of memory, chances are you can't find it in stores, and that the manufacturer charges you an arm and a leg for it. But with Crucial's memory selector you simply select the manufacturer of your PC and the model to get a list of all the memory that works with it - guaranteed. Conclusion Now that you're armed with all that knowledge, you should be able to confidently get the right memory upgrade for your system. As long as you do your homework and prepare for the upgrade with a little bit of research, upgrading your PC's RAM should be easy. http://www.PCNineOneOne.com