"Starting out as IBM PC Server, rebranded Netfinity, then eServer xSeries and now System x, these servers are distinguished by being based on off-the-shelf x86 CPUs; IBM positions them as their ""low end"" or ""entry"" offering. Previously IBM servers based on AMD Opteron CPUs did not share the xSeries brand; instead they fell directly under the eServer umbrella. However, current AMD Opteron-based servers fall under the System x brand"