4GB 400MHz DDR2 ECC Registered CL3 DIMM (Kit of 2) Dual Rank, x8...Standard 256M X 72 ECC 400MHz 240-pin Registered DIMM (SDRAM-DDR2, 1.8V, CL3). ValueRAM's KVR400D2D8R3K2/4G is a kit of two 256M x 72-bit 2GB (2048MB) DDR2-400 CL3 SDRAM (Synchronous DRAM) "dual rank" registered ECC memory modules. Total kit capacity is 4GB (4096MB). The components on each module include eighteen 128M x 8-bit (16M x 8-bit x 8 Bank) DDR2-400 SDRAM in FBGA packages. Each 240-pin DIMM uses gold contact fingers and requires +1.8V.