Sony PCG C Series of laptops includes 19 models. The computers come with memory already installed, but replacement memory is available for upgrading or repairing the system. The computers have internal memory card sockets, making replacing or upgrading the RAM easy to do. Like other personal computers, Sony PCG C Series laptops use non-ECC, non-registered and unbuffered RAM. All RAM comes with a 30 day money-back guarantee. The laptops use SO-DIMM chips, which are half the size of regular DIMMs. The smaller chips are designed for compact spaces, like laptops, printers and other small devices.