Dual Inline Memory Modules, or DIMMs, refer to the physical size and form factor of desktop memory modules. If you want to upgrade your desktop's memory but don't have the money to replace all modules with a single type and speed, you can mix the speed. The type, however, must remain the same. Most modern PCs use either Double Data Rate, DDR2 or DDR3 memory, this specification needs to stay the same; you cannot install DDR2 into a DDR3 or DDR system and you cannot mix the three types.
Things You'll Need
- Desktop's manual
- Phillips screwdriver (in most cases)
- Replacement DIMMs
Understanding and Preparing
Read your desktop's memory specifications before you buy any DIMMs, they're usually in the PC's manual. Pay attention to the type of memory, DDR, DRR2 or DDR3 in most cases. Also note the speed, usually written with "PC," "PC2" or "PC3," depending on whether it's DDR, DDR2 or DDR3. After the "PC" will be a number that denotes the memory's peak transfer rate in megabytes-per-second, the memory's optimum speed.
Buy your upgrade while keeping in mind that you need the same DDR type already installed. The number after "PC" may be different since faster memory within each specific type is backward-compatible with systems designed for slower memory. It's important to note that faster memory will run at the speed of the slowest installed module so if you have one PC2-3200 module and three PC2-8500 module, the PC2-8500's will perform at PC2-3200 speed.
Read the manual's section about upgrading memory. Most computer manual's provide a step-by-step guide specifically tailored to that PC, whereas a general memory upgrade guide's steps may differ, causing confusion or an improper upgrade.
Turn your PC off and unplug the power cable from the wall outlet, then from the desktop's tower. Remove all cords connected to the tower, like the monitor, your keyboard and any other connected peripherals.
Follow the steps laid out in the manual to upgrade your RAM. You'll have to remove a side panel from your Desktop's tower to do so. This often requires a Phillips screw driver but some desktops use other methods, such as securing lock buttons for easier access.
Tips & Warnings
- While it may seem cheaper to just buy one faster module and leave the slower modules, you're actually wasting money since the faster, more expensive memory will run at the speed of the slowest installed module. The best options are to either wait to upgrade until you can upgrade all module slots with the higher-speed memory or to upgrade using the speed already in your computer, simply installing more than you already have.
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