If you have just upgraded memory on a computer from 1 GB to 2 GB by adding one DIMM. When you first turn on the PC the memory count shows only 1 GB. Select is most likely the source of the problem?

The most likely source of the problem is that the new DIMM is not properly seated in its slot or is incompatible with the existing memory. It's also possible that the motherboard does not support the additional memory or that there is a BiOS setting that needs to be adjusted. Additionally, if the new DIMM is faulty, it could prevent the system from recognizing the full amount of memory. Checking the installation and compatibility of the DIMMs is a good first step in troubleshooting.