COMPTIA A+ Practice Exam

The correct answer is 533MHz. PC2-4200 refers to a type of DDR (Double Data Rate) SDRAM memory module, specifically DDR2. The "4200" in its designation indicates the theoretical bandwidth of the memory, which translates to 4.2 GB/s.

To determine the frequency of PC2-4200, it's important to understand how DDR memory operates. DDR memory transfers data on both the rising and falling edges of the clock cycle, effectively doubling the data rate. For DDR2, the effective memory data rate is calculated as follows:

- The "2" in "PC2" means it's operating at double data rate.

- The effective data transfer rate is 4200 MT/s (mega transfers per second).

- To find the actual clock frequency, you would divide the effective data rate by 2 (since DDR transfers data on two edges).

Thus, 4200 MT/s divided by 2 gives you a base clock frequency of approximately 533MHz. This is why 533MHz is the correct choice among the options.