Dell OptiPlex 7770 All In One OptiPlex 7770 All-in-One Service Manual - Page 8

2 Technology and components This chapter details the technology and components available in the system. Topics: • DDR4 • USB features • HDMI DDR4 DDR4 (double data rate fourth generation) memory is a higher-speed successor to the DDR2 and DDR3 technologies and allows up to 512 GB in capacity, compared to the DDR3's maximum capacity of 128 GB per DIMM. DDR4 synchronous dynamic random-access memory is keyed differently from both SDRAM and DDR to prevent the user from installing the wrong type of memory into the system. DDR4 needs 20 percent less or just 1.2 volts, compared to DDR3 which requires 1.5 volts of electrical power to operate. DDR4 also supports a new, deep power-down mode that allows the host device to go into standby without needing to refresh its memory. Deep power-down mode is expected to reduce standby power consumption by 40 to 50 percent. Key Specifications The following table lists the specifications' comparison between DDR3 and DDR4: Table 1. DDR3 vs DDR4 Feature/Option DDR3 DDR4 Chip Densities Data rates Voltage 512 Mb-8 Gb 800 Mb/s-2133 Mb/s 1.5 V 4 Gb-16 Gb 1600 Mb/s-3200 Mb/s 1.2 V Low voltage standard Internal banks Bank groups (BG) VREF inputs tCK - DLL Enabled tCK - DLL Disabled Read Latency Write Latency DQ Driver (ALT) DQ Bus RTT Values (in &Omega) RTT not allowed ODT Modes Yes (DDR3L at 1.35V) 8 0 2 -DQs and CMD/ADDR 300 Mhz-800 Mhz 10MHz - 125MHz (optional) AL+CL AL+CWL 40&Omega SSTL15 120,60,40,30,20 READ Bursts Nominal, Dynamic Anticipated at 1.05V 16 4 1 - CMD/ADDR 667Mhz-1.6Ghz Undefined to 125MHz AL+CL AL+CWL 48&Omega POD12 240,120,80,60,48,40,34 Disables during READ Bursts Nominal, Dynamic,Park ODT Control ODT Signaling Required ODT Signaling Not Required DDR 4 Advantages Larger DIMM capacities Migration to higher speed I/O Reduced memory power demand Memory Power Reductions Higher data rates Faster burst accesses VREFDQ Now Internal Higher data rates DLL-off now fully supported Expanded values Expanded values Optimal for PtP Applications Less I/O Noise and Power Support for higher data rates Ease of use Add'l Control Mode; OTF Value Change Ease of ODT Control; Allows Non-ODT Routing, PtP Apps 8 Technology and components