DDR5 RAM Advantages | Will it make a difference?

Here are the primary advantages of DDR5 RAM in brief.

DDR5 RAM
DDR5 RAM
ParametersAdvantage
Data RatesIncreases bandwidth and performances
Voltage (Power Usage)Lowers power consumption
Input Reference VoltageImproves voltage margins and reduces BOM costs
Device densitiesEnables bigger monolithic devices
Prefetch TechnologyKeeps internal core clock low
DQ Receiver equalizationImproves the opening of received DQ data eyes inside the DRAM
Duty Cycle AdjustmentImproves signaling on the transmitted DQ/DQS pins
Internal DQS Delay MonitoringIncreases robustness against environmental changes
On-die ECCStrengthens on-chip RAS
CRCStrengthens system RAS
Bank GroupsImproves bandwidth performance
Command Address interfaceReduces CA pin count
ODTImproves signal integrity and reduces BOM costs
Burst LengthAllows higher cache line fetch with a single DIMM channel
MIRImproves DIMM signaling
Bus InversionReduces V(DDQ) noise on modules
CA/CS TrainingImproves timing margin on CA/CS pins
Write leveling training modesCompensates for unmatched DQ-DQS path
Read Training patternsRobust read timing margin
Mode RegistersProvides room to expand
Pre-charge CommandsEnables pre-charging specific bank in each BG
Refresh CommandsREFsb enables refreshing of a specific bank in each BG
Loopback ModeEnables testing of DQ and DQS signaling

DDR5 RAM is a significant improvement over DDR4 as it beings a robust list of exciting features that increase availability, serviceability, reliability and improve performance while reducing power consumption. Here are the advantages of DDR5 explained in detail.

Data Rates

Compared to DDR4 that displays data transfer rates in the range of 1600 to 3200 MT/s, DDR5 doubles the capacity to display transfer rates of 3200 to 6400 MT/s. Therefore, it improves the overall performance and bandwidth.

teamgroup DDR5 ram

Power Consumption

The supply input voltage (VDD) and supply output voltage (VDDQ) in DDR5 RAM is lower at 1.1V compared to 1.2V in DDR4 RAM. In addition, the programming power voltage (VPP) is also lower at 1.8V as against 2.5V in DDR4. Hence, it translates into lower power consumption by DDR5 RAM.

Related: DDR5 vs DDR4

Input Reference Voltage

DDR5 RAM introduces input reference voltage for the Command and Address pins (VREFCA) and Chip Select pin (VREFCS) in addition to the DQ pins (VREFDQ). In contrast, DDR4 has only VREFDQ. Therefore, it improves voltage margins and reduces BOM costs by eliminating the requirement of an external reference voltage on the board.

Device Densities

DDR5 RAM supports higher capacity DRAM devices as the buffer chips DIMMs can use densities up to 64GB in a single-die package. In comparison, DDR4 has a maximum capacity of 16GB. Thus, DDR5 can support larger monolithic devices.

Prefetch Technology

DDR5 works on 16n Prefetch Technology compared to DDR4’s 8n. Hence, it enables higher data rates while maintaining the internal core clock range similar to DDR4.

DC Receiver Equalization

DDR5 supports multi-tap DFE, whereas DDR4 does not. Thus, it opens up the DQ data eye inside the DRAM, automatically resulting in higher data rates.

Duty Cycle Adjustment

Adjusting the duty cycle inside the DRAM enables the RAM controller to compensate for the duty distortion on all DQ and DQS pins. Therefore, it improves the overall signaling function.

Image Credit: Micron

Internal DQS Delay Monitoring

DDR5 features a DQS interval oscillator that provides a method for the RAM controller to decide on re-training based on DRAM delay changes caused by voltage and temperature variations. Thus, it strengthens the RAM against environmental changes.

Related: Intel 11th Gen vs 12th Gen

On-Die ECC

DDR5 strengthens on-chip RAS because of the 128b plus 8b SEC (error check and scrub), reducing the controller’s burden.

ERC

By strengthening on-system RAS, DDR5 protects R/W (Read and Write) data, whereas DDR4 protects the ‘Write’ data alone.

Bank Groups

DDR5 uses a 32-bank structure with eight bank groups compared to DDR4’s 16-bank design. Hence, it doubles the memory access availability and improves bandwidth. In addition, DDR5 adopts the Same Bank refresh Function that allows the next-gen memory to access other memory banks.

Command Address Interface

DDR5 requires two cycles for some commands. Thus, it reduces the CA Pin count drastically.

ODT

DDR5 eliminates the external termination resistor network for the CA bus. Thus, it saves BOM costs while CA ODT enhances signal integrity.

Burst Length

DDR4 has a burst rate of 8 to allow transfers up to 16GB from the cache. DDR5 enhances it to 16 with support for a 32-length mode. Thus, it can allow up to 64-byte cache line fetching performance with one DIMM.

Mirror Pin (MIR)

DDR5 has MIR that allows for shorter traces for clamshell modules and board designs to improve DIMM signaling.

Bus Inversion

DDR5 has Command Address Inversion compared to Data Bus Inversion in DDR4. Thus, it helps reduce power and noise on the VDDQ rail.

CA/CS Training

DDR4 has Write leveling training alone, whereas DDR5 supports CA and CS training besides Write leveling training mode. Thus, it improves the timing margin on VA and CS pins to enable faster data rates. Besides, the Write leveling training compensates for the device’s DQ-DQS path, enabling it to support fast data rates with a short write preamble. Thus, it enables shorter bus turnarounds.

Read Training patterns

Though Read training is possible in DDR4 with the MPR, DDR5 has dedicated MRs for the serial, clock, and LFSR-generated training patterns. These dedicated Read training patterns provide a stronger read timing margin, especially at high data rates.

Mode Registers

DDR5 supports up to 256 x 8 bits (LPDDR type R/W). Hence, it offers more room for expansion to support new features and improvements, proving its scalability.

Related: GDDR5 vs GDDR6

PRECHARGE Commands

This facility enables the pre-charging of a specific bank in each bank group while maintaining the active state of other banks unchanged.

REFRESH Commands

The Same bank Refresh feature enables refreshing a specific bank in each group while keeping the other banks available for access.

Loopback Mode

DDR4 does not offer this facility, while DDR5 does. It enables the testing of DQ and DQS signaling between DRAM and the controller. In addition, it helps isolate the actual memory array since the R/W accesses are not necessary.

Final Thoughts

These advantages of DDR5 sets the bar higher for overall system performance, push the limits of high-speed signaling, and address the memory bandwidth challenges.

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