A technician is performing a memory upgrade by installing an additional 1GB stick of DDR RAM into a system. When the installation is complete, the computer shows 2GB of RAM at POST; however, it now indicates a lower speed setting for the memory. Which of the following is the MOST likely cause?（）

• A、The newly installed RAM has a lower clock speed than the existing RAM.
• B、The CPU is not configured to work with the additional RAM.
• C、The system is incompatible with the new RAM.
• D、The new RAM is of lower quality, and not dependable at higher speeds.