Athlon II X4 638 is a desktop processor from AMD released on 6 February 2012, and it is in cpu.details.production-unknown now. It belongs to Athlon II X4 family and has a Llano architecture. This processor is built on AMD Socket FM1, and uses unknown PCI express connection. 32 nm process is used in production.
Processor has 4 cores and 4 threads, with the base frequency of 2.7 GHz. It has DDR3 Dual-channel memory support. As for the cache, it supports L1 128K (per core) and L2 1MB (per core).