Mushkin HP-Compaq 512MB DDR2 PC2-3200. Internal memory: 512 MB, Internal memory type: DDR2, Memory clock speed: 400 MHz. Memory voltage: 1.8 V. Compatibility: 382505-001 (HP/Compaq); P9907AX (HP/Compaq); PR662A (HP/Compaq); PU016-69001 (HP/Compaq)