Which type of memory is compatible with HP Z440, Z640, and Z840 workstations? 05/14/2017 – by Mod_GuideK 0 Which type of memory is compatible with HP Z440, Z640, and Z840 workstations? A. DDR1 B. DDR2 C. DDR3 D. DDR4 SHOW ANSWERSCorrect Answer: D Explanation/Reference: References: Download Printable PDF. VALID exam to help you PASS.