Review Index:

Memory: From Basics to Buying

Author: Ryan Shrout
Subject: Memory
Manufacturer: Corsair Components

Memory Installation

The actual installation part is easiest. Some tips while installing memory:

  • Open your computer case and locate the memory sockets on your motherboard. You may need to unplug cables and peripherals, and re-install them afterward.
  • Always handle the module by the edges.
  • Properly ground yourself before taking your RAM in hand; simply grab hold of an unpainted metal surface, such as the frame inside your PC. But if you tend to get zapped when you touch metal objects in the vicinity of your PC, consider more drastic measures before opening that ram packaging and get yourself a grounding wrist strap. Antistatic straps usually cost less than $10 and should be available where memory products are sold. If not your local electronic part supply house will have them. Electro-Static Discharge (ESD) is a frequent cause of damage to the memory module. ESD is the result of handling the module without first properly grounding yourself and thereby dissipating static electricity from your body or clothing. If ESD damages memory, problems may not show up immediately and may be difficult to diagnose.
  • DIMMs usually slide straight down into the slot and lock into place, when a little pressure is applied to each side of module itself and this is secured by the ejector tabs/clips on the ends of the slots which automatically snap into a locked position. Note how the module is keyed to the memory socket. This ensures the module can be plugged into the slot one way only -- the right way. You can probably determine how your PC's modules snap in by looking at the already installed memory. Repeat this procedure for any additional modules are installing. If you're removing RAM, the process is reversed--unlock the module by pushing out the clips, then lifting it up.
  • With the memory in place, turn on your PC. You should see evidence of your newly installed memory as the system does its power-on test (POST). If you don't or if a memory error appears or is heard then remove and re-seat all the memory modules--the old and the new. If this doesn't solve the problem, remove the new modules and try again.
  • Do not remove any stickers from the modules. Removing these stickers will likely void the warranty. The information present on these stickers maybe required for warranty replacement and information, as well as determining which module you have and its characteristics. These stickers will not have any affect on performance nor will they be affected by the heat inside the system.

Mixing DRAM

Mixing memory speeds refers to the use of more than one DRAM; each of which holds unlike properties such as speed, arrangement, size and even SPD programming. It doesn't always work as expected and so, it is generally preferable to avoid doing this. Often, many folks who upgrade machines, particularly older ones, find themselves in a situation where they may not be able to find additional memory that is identical to that which is already in the machine. The risks of running into problems are greatly increased if the modules used have significantly different properties. A system will only run at speed of the slowest module, if you mix different speed modules. As you will see, some systems automatically detect the properties of memory modules being used, and set the system timing accordingly. They usually look at the speed of the memory in the first bank when setting this timing. So if you use two or more dissimilar modules, it is advisable to place to the slowest module in the first slot.

As well, if the goal is overclocking, often the best results are obtained with perfectly matched modules. Additionally dual channel architectures generally work very poorly with mis-matched modules. There is no guarantee a mismatch won't work for one reason or another, and it won't really hurt anything to try (assuming your data is backed up), but to maximize the chances of success, modules should match.

Which slots to use?

  • If you're using a single module, it's best practice to use the first slot. If using two or more modules in a non-dual channel motherboard, populate the first slot and use any other slots you wish. Q: I've had my single module installed in slot 2 for the last few months now, should I change it? No, it's also best practice to keep on using the slot(s) you're been using before. If you replace RAM, then insert the new modules, in the same slots the older ones were in before.
  • You may find the system overclocks better with the ram in a different slot. It is very hard to predict when this effect occurs, as well as which one might work best. In the overclocking game he who tries the most things wins, and if you are running an overclocked configuration that is asking a lot of the ram it is a good idea to try all available slots to make sure the one you are using yields the best results.
  • If you're using two or more modules of unequal size, you will get the best performance if you put the largest module(s) (in megabytes) in the lowest-numbered slot(s). For example, if your system currently has 256MB of memory and you want to add 512MB, it would be best to put the 512MB module into slot 0 and the 256MB module into slot 1.

Using Dual Channel

Dual Channel requires at least two modules for operation. It is recommended that the modules you use be of the same size, speed, arrangement etc. Dual Channel is optional on the original nforce2 motherboards and nforce2 ultra400. You can also choose to run in single channel mode on these motherboards. Nforce2 400 boards are singe-channel only. Most dual channel capable nforce2 motherboards come with three slots. On these motherboards the first memory controller controls only the first slot (or the slot by itself), while the second memory controller controls the last two slots (which are usually closer together). Name them slots 1, 2 & 3 respectively. To implement Dual Channel, it is necessary to occupy the slot 1 (channel 0) and either one of the two slots that are closer together, slots 2 or 3 (channel 1). The entire config would be running in 128 bit mode.

You can use three modules in Dual Channel Mode, by filling the third unoccupied slot. With three sticks, slots 1 remains as channel 0 while slot 2&3 become channel 1. To maintain 128-bit mode, with all three slots filled, each channel must have an equal amount of memory. For example, slots 1 should be filled with a 512 Mb module, while slots 2 & 3 are populated 256 Mb modules. If you were to use three modules of the same size, then only the first two modules would be running in 128 bit Dual Channel Mode. Example, using 3x 256 Mb modules will have the first 512 Mb running in 128 bit Dual Channel mode, while the remaining 256 Mb will be in 64-bit Single Channel mode.

Intel dual-channel systems are different. The have either two or four slots, and to run dual channel mode must have either one or two pairs of (hopefully) matching modules. Running three modules on a P4 system will force it to run in single channel mode, and is therefore to be avoided.

Consult your motherboard manual for instruction on exactly which slots exactly to use.