What is the difference between DDR4 and DDR3?

1.DDR4 Memory strip appearance changes obviously, the gold finger becomes the curved shape

2.DDR4 memory frequency boost, up to 4266MHz

3.DDR4 memory capacity increased significantly, up to 128GB

4.DDR4 power consumption is significantly reduced, with voltages up to 1.2V or even lower

Many computer users may not have much attention to the internal improvement of memory, and the external changes are more likely to be discovered, always, the memory of the gold fingers are straight, and in the DDR4 this generation, the memory of the gold finger has changed significantly, it is become bent, in fact, has been, In order to solve this problem, DDR4 will design the lower part of the memory into a slightly protruding, edge-less shape, after the straight memory is inserted into the memory slot and the friction is large, so the memory is difficult to unplug and difficult to insert. The central highs and lows at both ends are smoothed with a smooth curve transition. Such a design can ensure that the DDR4 memory of the gold finger and memory slot contacts have enough contact surface, signal transmission to ensure that the signal is stable, so that the middle convex part and the memory slot to generate enough friction to stabilize the memory.

Second, the DDR4 memory of the gold finger itself design has a more obvious change. The "Notch" in the middle of the gold finger is the position of the anti-DDR3, which is closer to the center than the. In terms of the number of gold finger contacts, the average DDR4 memory has 284, while the DDR3 is 240, each contact distance from 1mm reduced to 0.85mm, notebook memory used SO-DIMM DDR4 memory has 256 contacts, SO-DIMM DDR3 has 204 contacts, The pitch was reduced from 0.6 mm to 0.5 mm.

Third, the standard size of the DDR4 within the PCB, length and height, but also made a certain adjustment. Due to the DDR4 chip packaging and the need for high density, large capacity, so DDR4 PCB layer than DDR3 more, and the overall size has a different change, such as the above figure.

Huge frequency and bandwidth boost

DDR4 's most important mission, of course, is to increase frequency and bandwidth. Each pin of the DDR4 memory can provide 2Gbps (256mb/s) bandwidth, ddr4-3200 that is 51.2gb/s, higher than the ddr3-1866 of more than 70%. In the process of DDR development, it has always been to increase the data prefetch value as the main performance improvement means. But in the DDR4 era, the increase in data prefetching became more difficult, so the bank group design was introduced.

What is the bank group structure like? Specifically, each bank group can read and write data independently, so that the internal data throughput is greatly improved, can read a large amount of data at the same time, the equivalent frequency of memory in this setting also greatly improved. The DDR4 architecture employs a 8n prefetch bank Group grouping, which includes the use of two or four selectable bank group groupings, which will allow separate activation, read, write, and refresh operations for each bank group of DDR4 memory, thereby improving overall memory efficiency and bandwidth. This way, if the internal memory design of two independent bank group, equivalent to 16bit per operation of data, in disguise to increase the memory pre-value to 16n, if it is four independent bank group, the disguised pre-fetch value is increased to 32n.

If Bank Group is a key technology for DDR 4 memory bandwidth boost, then point-to-point bus is the key design of DDR4 whole storage system, for DDR3 memory, the current mechanism of data read access is two-way transmission. In DDR4 memory, the access mechanism has been changed to point-to-point technology, which is the key design of DDR4 whole storage system.

In DDR3 memory, the connection between the memory and memory controller is achieved through a multipoint branch bus. This bus allows the mounting of many identical chips on an interface. We all know that the current motherboard is often designed for dual channel design four memory slots, but each channel on the physical structure only allow the expansion of larger capacity. The feature of this design is that when the amount of data transmitted exceeds the load carrying capacity of the channel, no matter how much you increase the memory capacity, the performance is not increased. This design is like in a main pipeline can have more than one water injection pipe, but the size of the control channel, even if you can increase the water injection tube to improve capacity, but the total water delivery rate does not improve. So in this case may 2GB increase to 4GB you will feel the performance improvement is obvious, but continue to blindly increase capacity is meaningless, so the advantage of Multipoint branch bus is to expand the memory easier, but wasted memory bit width.

As a result, DDR4 abandoned the design in favor of a point-to-point bus: The memory controller can only support a single memory per channel. Compared to Multipoint branch bus, point-to-point is equivalent to one main pipe only one water injection tube, so the design benefits can greatly simplify the design of the memory module, more easily reach a higher frequency. However, the issue of point-to-point design is equally obvious: one important factor is that the point-to-point bus can only support one memory per channel, so if the DDR4 has insufficient capacity, it will be difficult to effectively increase the total memory of the system. Of course, this is difficult for developers, 3DS Packaging technology is the key technology to amplify DDR4 capacity.

　Capacity surge up to 128GB

3DS (3-dimensional stack, three-dimensional stacking) technology is one of the most critical technologies in DDR4 memory, which is used to increase the capacity of a single chip.

3DS technology was originally America, it is similar to the traditional stacking packaging technology, such as the mobile phone chip processor and memory are stacked on the motherboard to reduce the volume-stacking welding and stacking the difference is that one after the chip package is completed, stacked on the PCB board, and the other before the chip package, Stacked inside the chip. In general, in the case of heat dissipation and process permitting, the stacking package can greatly reduce the chip area, which is very helpful for miniaturization of products. On the DDR4, the stacking package is mainly implemented in the form of TSV silicon perforation.

The so-called silicon perforation, laser or etching on the silicon wafer to drill holes, and then fill in the metal connecting holes, so that the silicon perforation of the different wafers between the signal can be transmitted to each other. With the use of 3DS stacking packaging technology, the capacity of a single memory can be up to 8 times times the current product. For example, the current common large capacity memory single capacity of 8GB (one chip 512MB, a total of 16), and DDR4 can achieve 64GB, or even 128GB.

Lower power consumption and lower voltage

Lower voltage: This is an essential element of each generation of DDR evolution, DDR4 has dropped to 1.2V

Let's start with the power consumption aspect. DDR4 memory is TCSE (temperature compensated self-refresh, temperature compensated self-flushing, mainly used to reduce the power consumed by the memory chip during self-refresh), tcartemperature compensated Auto Refresh, temperature compensation auto Refresh, similar to T CSE), DBI (data bus inversion, data bus inverted, to reduce VDDQ current, reduce switching operation) and other new technologies.

These technologies can reduce the power consumption of DDR4 memory in use. Of course, the most straightforward way to reduce power consumption as a new generation of memory is to use newer processes and lower voltages. At present, DDR4 will be manufactured using a process below 20nm, the voltage from DDR3 1.5V to DDR4 1.2V, the mobile version of the SO-DIMMD DR4 voltage will also drop lower. The power performance of the DDR4 will be excellent as process progresses, voltage drops, and combined use of multiple power control techniques.

People's expectations of DDR4 is quite high, for its listing has been waiting for a long time, but to know that DDR3 took a full three years to complete the replacement of DDR2, and DDR4 ambition is mostly, although to the end of this year will be officially debut, but next year will have to occupy half, Become the new mainstream specification. Next, let's take a look at the recent production releases about DDR4 memory for each manufacturer.

　　Supports next-generation processor DDR4 memory exposure

Wei just recently formally announced their first DDR4 memory products, Granville first DDR4 not many, only the standard server-type ECC RDIMM, capacity 4GB, 8GB, 16GB, rated frequency is also 2133MHz, voltage 1.2, product number AD4R2133W4G15, AD4R2133Y8G15, Ad4r2133y16g15.

However, Wei just said that the DDR4 version of ECC So-dimm, VLP RDIMM, LRDIMM and other types are also being developed, will soon be introduced.

These memory are used by servers and workstations, and Wei Gang said they have been working closely with Intel, and its DDR4 memory fully supports the next-generation server platform Haswell-ep Xeon e5-2600 v3.

As for the consumer-grade DDR4 memory, no one has any news, but Intel will launch its first DDR4-supported desktop Fever platform in the third quarter haswell-e, believing that there will soon be new memory to keep up.

2400MHz DDR4 Pilot-run DDR4 large-scale construction of beauty light

Wei just announced their first DDR4 memory products earlier, the U.S. light is not outdone, announced that its DDR4 memory has been large-scale production, and gradually increase production.

Mei Guang said that the current production of 4Gb DDR4 memory particles, the standard frequency of 2133MHz, and in particular, in cooperation with Intel, for the second half of the release of the next-generation server platform Xeon E5-2600 V3 is optimized.

The new platform architecture, based on 22nm Haswell-ep, will replace the Ivy Bridge-ep e5-2600 v2 released last September, primarily for the dual server domain.

The current release of DDR4 memory frequency is only 2133MHz, which is actually DDR3 can easily reach the height, naturally can not highlight the advantages of new memory. The 2400MHz DDR4 is in trial production and is expected to be formally put into operation in 2015 (that is, not expected this year), the U.S. light said.

Mei Guang also revealed that they will continue to roll out the full product line that complies with the JEDEC DDR4 standard, covering RDIMM, LRDIMM, VLP RDIMM, Udimm, SO-DIMM various specifications, ECC can also be optional, to the beginning of the third quarter of this year will increase NVDIMM.

　Narrow strip compatibility strong Virtium release DDR4 memory

DDR4 Memory finally fully bear fruit. Embedded storage Vendors Virtium today also launched their DDR4 products, and very special, for the first time using the ULP ultra-small size, a height of only 17.8 mm (0.7 inches).

The standard height of the DDR4 DIMM memory is 31.25 mm, slightly higher than DDR3 30.35 mm, while the So-dimm height on the notebook is 30 mm, and the VLP for high-density servers is only 18.3-18.7 mm (0.72-0.738 inches) in size.

ULP is the most compact of all types, only half the standard type, suitable for space-tight embedded fields.

Virtium ULP DDR4 Memory is also server-type URIMM, single capacity 4GB (rank), 8GB (double rank), 16GB (double rank), standard frequency 2133MHz, standard voltage 1.2V, standard tolerance temperature range 0~85℃, expansion/ Industrial withstand temperature range -25/-40~95℃, five year warranty.

Virtium says the memory has been tested and validated by customers and is coming in bulk.

　DDR4 becomes active Samsung accelerates production of DDR4 memory particles

This time, the large memory particles, module manufacturers are suddenly active, have to promote their own DDR4 product progress, and as the DRAM industry leader, the first production DDR4 Samsung Electronics How can remain silent? The South Korean giant recently announced that it is accelerating the production of DDR4 memory particles, memory chips.

Waigang, like the United States, Samsung also specifically mentioned that Intel will be released in the second half of the next generation of server platform Haswell-ep Xeon e5-2600 v3, said its own DDR4 memory is prepared for the platform.

Samsung has already produced DDR4 memory is a single Die 4Gb (512MB) capacity, to provide x4, x8, x16 and other different chip package specifications, a single capacity of up to 32GB, the frequency is the standard 2133MHz, the specification covers Rdimm, LPDIMM, ECC SODIMM and so on.

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