Difference between DDR3 and DDR4 RAM

DDR4 is the next evolution in DRAM, bringing even higher performance and more robust control features while improving energy economy for enterprise, micro-server, tablet, and ultrathin client applications. The following table compares some of the key feature differences between DDR3 and DDR4.

  Feature/Option

        DDR3

      DDR4

  DDR4 Advantage

Voltage (core and I/O)

1.5V

1.2V

Reduces memory power demand

VREF inputs

2 – DQs and CMD/ADDR

1 – CMD/ADDR

VREFDQ now internal

Low voltage standard

Yes 

(DDR3L at 1.35V)

Anticipated 

(likely 1.05V)

Memory power reductions

Data rate (Mb/s)

800, 1066, 1333, 1600, 1866, 2133

1600, 1866, 2133, 2400, 2667, 3200

Migration to higher‐speed I/O

Densities

512Mb–8Gb

2Gb–16Gb

Better enablement for large-capacity memory subsystems

Internal banks

8

16

More banks

Bank groups (BG)

0

4

Faster burst accesses

tCK – DLL enabled

300 MHz to 800 MHz

667 MHz to 1.6 GHz

Higher data rates

tCK – DLL disabled

10 MHz to 125 MHz (optional)

Undefined to 125 MHz

DLL-off now fully supported

Read latency

AL + CL

AL + CL

Expanded values

Write latency

AL + CWL

AL + CWL

Expanded values

DQ driver (ALT)

40Ω

48Ω

Optimized for PtP (point-to-point) applications

DQ bus

SSTL15

POD12

Mitigate I/O noise and power

RTT values (in Ω)

120, 60, 40, 30, 20

240, 120, 80, 60, 48, 40, 34

Support higher data rates

RTT not allowed

READ bursts

Disables during READ bursts

Ease-of-use

ODT modes

Nominal, dynamic

Nominal, dynamic, park

Additional control mode; supports OTF value change

ODT control

ODT signaling required

ODT signaling not required

Ease of ODT control, allows non-ODT routing on PtP applications

Multipurpose register (MPR)

Four registers – 1 defined, 3 RFU

Four registers – 3 defined, 1 RFU

Provides additional specialty readout

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