4GB Total memory using 2pc of 2GB 1333MHz Module 240pin dimm DDR3 10600. Also 1066mhz will work high density Supports DDR3 2000 (OC) /1866*/1800*/1600*/1333/1066/800 non-ECC, un-buffered memory Lifetime warranty for exchange BY Computer Memory Solutions BRAND Computer Memory Solutions We don't use Generic modules to avoid incompatibility issues. Guaranteed to work or you get all of your money back including shipping. MAX MEMORY 32GB SOCKETS 4 COMPATIBLE WITH ASRock Motherboard 890GX Extreme4 R 2.0, 960GC-GS FX