Service Manual

Feature/Option DDR3 DDR4 DDR 4 Advantages

DQ Bus SSTL15 POD12 Less I/O Noise and Power

RTT Values (in &Omega) 120,60,40,30,20 240,120,80,60,48,40,34 Support for higher data rates

RTT not allowed READ Bursts Disables during READ Bursts Ease of use

ODT Modes Nominal, Dynamic Nominal, Dynamic,Park Add’l Control Mode; OTF Value

Change

ODT Control ODT Signaling Required ODT Signaling Not Required Ease of ODT Control; Allows

Non-ODT Routing, PtP Apps

Multi-Purpose Register Four Registers – 1 Dened, 3

RFU

Four Registers – 3 Dened, 1

RFU

Provides Additional Specialty

Readout

DIMM Types RDIMM, LRDIMM, UDIMM,

SODIMM

RDIMM, LRDIMM, UDIMM,

SODIMM

DIMM Pins 240 (R, LR, U); 204 (SODIMM) 288 (R, LR, U); 260 (SODIMM)

RAS ECC CRC, Parity, Addressability, GDM More RAS features; improved

data integrity

DDR4 Details

There are subtle dierences between DDR3 and DDR4 memory modules, as listed below.

Key notch dierence

The key notch on a DDR4 module is in a dierent location from the key notch on a DDR3 module. Both notches are on the insertion edge,

but the notch location on the DDR4 is slightly dierent, to prevent the module from being installed into an incompatible board or platform.

Figure 1. Notch dierence

Increased thickness

DDR4 modules are slightly thicker than DDR3, to accommodate more signal layers.

Figure 2. Thickness dierence

Curved edge

Technology and components