irst is the current peak capacity of memory modules available, and the second is the number of memory slots that exist in your motherboard. As of this writing, 4GB modules are widely available. Most midrange motherboards come with four memory slots and low-end models can have as few as two. That means that on your average midrange motherboard, you’ll be practically limited to 16GB of system memory, and low-end motherboards will be limited to 8GB. The third limiting factor is your operating system. Avid Smart Computing readers will also recall that processors were once a system memory barrier, but nearly every processor sold in the last five years is capable of accessing more than 4GB of memory. Although processors effectively punched through the 4GB system memory limit long ago, 32-bit, consumer-centric versions of Windows, including WinXP/Vista/7, recognize only capacities of 4GB or less. To determine if you’re running a 64-bit or 32-bit operating system, click Start, right-click Computer, and click Properties. Look under the System Type heading and you will see whether you’re running a 32-bit or 64-bit operating system. If you see 32-bit, then stick with 4GB of memory. If you see 64-bit, then feel free to purchase 4GB or more.