86  IBM z14 (3906) Technical Guide Enabled memory sizes GB 320 - 8000 320 - 16192  320 - 24384  320 - 32576 320 - 32576 Flexible memory sizes GB N/A 320 - 8000 320 - 16192  320 - 24384  320 - 24384  L1 cache per PU (I/D) 128/128 KB 128/128 KB 128/128 KB 128/128 KB 128/128 KB L2 cache per PU 2/4 MB (I/D) 2/4 MB (I/D) 2/4 MB (I/D) 2/4 MB (I/D) 2/4 MB (I/D) L3 shared cache per PU  chip 128 MB 128 MB 128 MB 128 MB 128 MB L4 shared cache per node 672 MB 672 MB 672 MB 672 MB 672 MB Cycle time (ns) 0.192 0.192 0.192 0.192 0.192 Clock frequency 5.2 GHz 5.2 GHz 5.2 GHz 5.2 GHz 5.2 GHz Maximum number of PCIe  fanouts 10 20 30 40 40 Maximum number of IFB  fanouts 4 8 12 16 16 I/O interface per IFB cable 6 GBps 6 GBps 6 GBps 6 GBps 6 GBps I/O interface per PCIe cable 16 GBps 16 GBps 16 GBps 16 GBps 16 GBps Number of support  elements 2 2 2 2 2 External AC power 3-phase 3-phase 3-phase 3-phase 3-phase Optional external DC 520 V/380 V 520 V/380 V 520 V/380 V 520 V/380 V 520 V/380 V Internal Battery Feature Optional Optional Optional Optional Optional Description Model M01  Model M02 Model M03 Model M04 Model M05