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amount of RAM, so one of the first laptop upgrades you’ll be called on to do is to add more RAM. Economy laptops running Windows XP Home routinely sit on store shelves and go home to consumers with as little 256 MB of RAM, an amount guaranteed to limit the use and performance of the laptop. The OS alone will consume more than half of the RAM! Luckily, every decent laptop has upgradeable RAM slots. Most older laptops use either 72-pin or 144-pin SO-DIMMs with SDRAM technology. DDR, DDR2, and DDR3 systems primarily use 200-pin SO-DIMMs, although some laptops use micro-DIMMs (Figure 21-20).

Figure 21-20 200-pin SO-DIMM stick (front and back)

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TIP The amount of RAM needed to run a PC—portable or otherwise—smoothly and stably depends on both the type of applications that it will run and the needs of the OS. When making a recommendation to a client about upgrading a laptop’s memory, you should ask the basic questions, such as what the client plans to do on the laptop. If the laptop will be used for e-mail, word processing, and Web surfing, a medium level of RAM, such as 1 GB, might be adequate for a Vista machine. If the user travels, uses a high-end digital camera, and wants to use Photoshop to edit huge images, you’ll need to augment the RAM accordingly. Then add the needs of the OS to give a good recommendation.

How to Add or Replace RAM Upgrading the RAM in a portable PC requires a couple of steps. First, you need to get the correct RAM. Many older portable PCs use proprietary RAM solutions, which means you need to order directly from Dell, HP, or Sony and pay exorbitant prices for the precious extra megabytes. Most manufacturers have taken pity on consumers in recent years and use standard SO-DIMMs or micro-DIMMs. Refer to the manufacturer’s Web site or to the manual (if any) that came with the portable for the specific RAM needed.

Second, every portable PC offers a unique challenge to the tech who wants to upgrade the RAM, because there’s no standard for RAM placement in portables. More often than not, you need to unscrew or pop open a panel on the underside of the portable (Figure 21-21). Then you press out on the restraining clips and the RAM stick pops up (Figure 21-22). Gently remove the old stick of RAM and insert the new one by reversing the steps.

Figure 21-21 Removing a RAM panel

Figure 21-22 Releasing the RAM

Shared Memory Some laptops (and desktops) support shared memory. Shared memory reduces the cost of video cards by reducing the amount of memory on the video card itself. Instead of having 256 MB of RAM, the video card might have only 64 MB of RAM, but be able to borrow 192 MB of RAM from the system. This equates to a 256 MB video card. The video card uses regular system RAM to make up for the loss.

The obvious benefit of shared memory is a less expensive video card (and a less expensive laptop!) with performance comparable to its mega-memory alternative. The downside is that your overall system performance will suffer because a portion of the system RAM is no longer available to programs. (The term shared is a bit misleading because the video card takes control of a portion of RAM. The video portion of system RAM is not shared back and forth between the video card processor and the CPU.) Shared memory technologies include TurboCache (developed by NVIDIA) and Hyper-Memory (developed by ATI).

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NOTE You cannot tell if a laptop is using shared memory in Windows. You have to go to CMOS to be sure.

Some systems give you control over the amount of shared memory, while others simply allow you to turn shared memory on or off. The settings are found in CMOS setup and only on systems that support shared memory. Shared memory is not reported to Windows, so don’t panic if you have 1 GB of RAM in your laptop but Windows only sees 924 MB—the missing memory is used for video.

Adding more system RAM to a laptop with shared memory will improve laptop performance. Although it might appear to improve video performance, that doesn’t tell the true story. It’ll improve overall performance