Dell Vostro 3267 Owner's Manual page 67

Table 4. DDR3 vs DDR4 (continued)
Feature/Option
DQ Bus
RTT Values (in &Omega)
RTT not allowed
ODT Modes
ODT Control
Multi-Purpose Register
DIMM Types
DIMM Pins
RAS
DDR4 Details
There are subtle differences between DDR3 and DDR4 memory modules, as listed below.
Key notch difference
The key notch on a DDR4 module is in a different 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 different, to prevent the module from being installed into an
incompatible board or platform.
Figure 1. Notch difference
Increased thickness
DDR4 modules are slightly thicker than DDR3, to accommodate more signal layers.
Figure 2. Thickness difference
Curved edge
DDR4 modules feature a curved edge to help with insertion and alleviate stress on the PCB during memory installation.
DDR3
SSTL15
120,60,40,30,20
READ Bursts
Nominal, Dynamic
ODT Signaling Required
Four Registers – 1 Defined, 3
RFU
RDIMM, LRDIMM, UDIMM,
SODIMM
240 (R, LR, U); 204
(SODIMM)
ECC
DDR4
POD12
240,120,80,60,48,40,34
Disables during READ Bursts
Nominal, Dynamic,Park
ODT Signaling Not Required
Four Registers – 3 Defined, 1
RFU
RDIMM, LRDIMM, UDIMM,
SODIMM
288 (R, LR, U); 260
(SODIMM)
CRC, Parity, Addressability,
GDM
Technology and components
DDR 4 Advantages
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
Provides Additional Specialty
Readout
More RAS features; improved
data integrity
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