A user already has 2 RAM modules in a 64-bit Windows 7 PC. Each is a 1GB DDR-PC1600 RAM module. The user has 2 additional RAM modules that are each 2GB DDR-PC800. Which of the following is true about the PC after installing the additional RAM modules?
A. The system only accesses the pair of 2GB RAM modules
B. The system accesses all RAM at 100MHz
C. The system enables ECC on all RAM modules
D. The system will not work as all RAM has to be equal sizes