Fully Buffered DIMM

Fully Buffered DIMM ( FB-DIMM or short FBDIMM ), DRAM modules, where the memory chips are not directly connected to the computer, but contain an additional component for the control ( buffer). They are regarded as the successor of Registered modules, both of which are used primarily for the server and workstation area. This property is used to DDR2 and DDR3 memory modules. In addition to the memory chips is an Advanced Memory Buffer (AMB ) on the DIMM circuit board. This module provides over 24 line pairs, similar to the serial PCI Express technology to connect to the memory controller ago. The FB- DIMM technology can manage up to eight modules per memory channel.

The serial interface of the AMB technology enables high performance and scalability. Advantage over parallel Registered DIMMs: increasing the storage capacity by about a factor of 24 and the memory bandwidth by approximately fourfold. Extensive data security features round out the concept. Disadvantages include increased power consumption and heat generation of the modules, mainly caused by the AMB. In addition a slightly increased latency time when compared to conventional (parallel) DDR ( 2) SDRAM, due to the error correction of the AMB chip.

Increased safety with respect to the error rate is accomplished by various methods. Silent Data Corruption Failure in Time ( SDC FIT rate ) is given by the factor 1000 lower than that of the overall system. ECC and CRC ( via data and commands) are well-known standards. Complemented by transient bit -error function bit errors are detected and data transferred again. The Path -through -path logic increases the availability of reliable data. Faulty data lines are detected by means of Bit Lane Fail - Correction and the data line is replaced (with internal redirect the signal line ) with a working. The AMB performs an Error register shall be recorded in the faulty memory locations - those are too many informed the diagnostic software system administrator.

The hot- add- function memory modules can be added during operation without the memory bank must first be deactivated. Since 2006 there first ( Motherboard ) chipsets that offer a corresponding memory support. This must, however, be supported by the operating system, otherwise the added memory is not recognized or used.

FBDIMMS have a different base than the usual DRAM modules. The Kodierkerbe is shifted in FBRAM to 8 mm to the right of the module center. In the conventional DRAM modules is only 4 mm.