This 64GB (2x32GB) RAM is 100% compatible with the HP Z1 G1i Tower. Information regarding memory configuration: The following technical specifications should be considered in advance: Non-ECC or ECC (Error-Correction-Code) RAM can be installed in the device. Modules labeled ECC have error correction. Non-ECC memory modules cannot be mixed with ECC memory. If a memory upgrade is to be made with the existing RAM, it must be checked which memory technology (non-ECC / ECC) is currently in use.