Why Should You Use DDR4 Over DDR3?

First you need to know what are DDR3 and DDR4 exactly?

What is DDR3?

In computing, DDR3 an abbreviation for Double Data Rate type three synchronous dynamic random access memory with a high bandwidth interface and has been in use since 2007.
It is a higher speed successor to DDR and DDR2 but predecessor to DDR4 synchronous dynamic random- access memory chips.
It is neither forward nor backward compatible with any earlier type of random- access memory because of different signalling voltages, timings and other factors.

While, DDR4, a double data fourth generation synchronous dynamic random access memory with a high bandwidth released to the market in 2014 is one of the latest variants of Dynamic Random Access Memory and a higher successor to DDR2 and DDR3 technologies.
It is not compatible with any earlier type of RAM due to different signalling voltages, physical interface and other factors.
The primary advantages of DDR4 over its predecessor, DDR3, include higher module density and lower voltage requirements, coupled with higher data rate transfer speeds.

Features	DDR3	DDR4	DDR4 Advantage
Data Transfer Rate (Mb/s)	800, 1066, 1333, 1600, 1866, 2133	1600, 1866, 2133, 2400, 2666, 3200	Migration to higher speed I/O
Module Density	512MB – 8GB	2GB – 16GB	Better enablement for large – capacity memory subsystems
Required Voltage	1.5 V	1.2 V	Reduces Memory Power demand
Internal Banks	8	16	More banks
DQ bus	SSTL15	POD12	Mitigate I/O noise power
ODT Control	ODT signals required	ODT signals not required	Ease of ODT control, allows non ODT routing on PtP applications
ODT Modes	Nominal, Dynamic	Nominal, Dynamic, Park	Additional control Mode; supports OTF value change
Multipurpose register	4 registers- 1 defined, 3 RFU	4 registers- 3 defined, 1 RFU	Provides additional Speciality Readout
Round -Trip Time ()	12, 60, 40, 30, 20	240, 120,80,60,48,40,34	Support higher data rates
DQ Driver	40Ω	48Ω	Optimized for PtP application