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Friday, 28. September 2012

DDR3 DDR2 and what is the difference?

By batteryline, 08:38
1. Burst length (BurstLength, BL)
Because the prefetch DDR3 for 8 bit, so burst transmission period (BurstLength, BL) also fixed for 8, and for DDR2 and early DDR architecture system, BL = 4 also is commonly used, DDR3 therefore added a 4 bitburstchop hp pavilion dv5-1003tx laptop cpu fan (sudden mutation) model, that is, by a BL = 4 read operation to plus a BL = 4 write operation for synthesis of a BL = 8 data burst transmission, when can through the A12 address line to control the burst mode. And it should be pointed out that, any sudden interrupt operation will be in DDR3 memory be prohibited, and will not support, instead more flexible burst transmission control (such as 4 bit sequence burst).
 
2. Addressing sequence (Timing)
Like DDR2 change from DDR to delay cycle number increases, the CL DDR3 cycle will also improve than the DDR2. The scope of CL DDR2 in commonly 2 ~ 5 between, and DDR3 is in 5 ~ 11 between, and additional delay (AL) design also change.hp pavilion dv5-1003xx laptop cpu fan When DDR2 AL range is 0 ~ 4, and DDR3 AL when there are three options, respectively is 0, CL - 1 and CL - 2. In addition, new DDR3 also added a sequence parameter - write delay (CWD), this parameter will according to the specific work frequency and decide.
 
3. DDR3 new Reset (Reset) function
Replacement is DDR3 added an important function, and specially prepared a pin. DRAM industry a long time ago to ask for an increase in the function, and now finally in DDR3 realized. This pin will make DDR3 initialization processing become simple. When Reset command effective, DDR3 memory will stop all operations, and switch to the most minor activity state, to save power.
 
In the Reset period, DDR3 memory will shut down most of the internal hp pavilion dv5-1004 laptop cpu fan function, all data reception and transmitter will be closed, all internal program device will Reset, the DLL (delay phase locked loop) and clock circuit will stop working, and ignore data bus of any action. In this way, will make DDR3 to reach the purpose of saving electricity.
 
4. DDR3 new ZQ calibration function
ZQ is also a new feet, in this pin connected to a 240 ohms low tolerance reference resistance. This pin through a command set, through the chip calibration engine (On - DieCalibrationEngine, ODCE) to automatic check data output driver On resistance and the end of ODT resistance. When the system issued this instruction, will use the corresponding clock cycle (at power up and initialization in 512 after a clock cycle, in exit from refresh operation in 256 after a clock cycle, in other cases with 64 clock cycle) conduction hp pavilion dv5-1004ax laptop cpu fan resistance and ODT resistance to recalibrate.
 
5. Reference voltage is divided into two
In DDR3 system, for memory system work very important reference voltage signal VREF will be divided into two signal, namely for command and address signal service VREFCA and for data bus service VREFDQ, which will effectively improve the system data bus signal-to-noise level.
 
6. Point to Point connection (Point - to - Point, P2P)
This is in order to improve the system performance and the important changes, but also with the DDR2 DDR3 a key difference. In DDR3 system, a memory controller only with a memory channel business, and this memory channel can only have a slot, therefore, the memory controller and DDR3 memory module are peer-to-peer (P2P) relationship (single physical Bank module), or Point hp pavilion dv5-1004ax laptop cpu fan to two Point (Point - to - two - Point, P22P) relationship (double physical Bank module), thus greatly reduced the address/command/control and data bus load. And in memory module, and similar DDR2 category, also have standard DIMM (PCS), SO - DIMM/Micro - DIMM (notebook computer), FB - DIMM2 (server) points, including the second generation of FB - DIMM will use specification higher AMB2 (amb).
 
Facing 64 framework DDR3 obviously in the frequency and speed has more advantages, in addition, because the DDR3 according to temperature automatic self refresh, local since refresh and other some functions, in power loss DDR 3 will much more outstanding, therefore, it may first by mobile equipment welcome, just like the first meet the DDR2 memory is not as desktops but hp pavilion dv5-1004el laptop cpu fan server. In the CPU by ascending the most rapid PC desktop field, DDR3 future is also a bright. Currently Intel in the second quarter next year is expected to the launch of the new chip - XiongHu (BearLake), which will support DDR3 specifications, and AMD also predicted that at the same time in K9 platform support DDR2 and DDR3 two specifications.
 
Memory asynchronous work mode contains a variety of meaning, in the broad sense all memory work frequency and CPU external clock do not agree can be called memory asynchronous work mode. First of all, the earliest memory asynchronous work patterns appeared in the early motherboard chipset, can make the memory work in than CPU by high 33 MHZ or low 33 MHZ mode (note simply differ 33 MHZ), which can improve the system memory performance or make old memory continue to play waste heat. Secondly, in normal working mode (CPU not overclocking), at present a lot of mainboard chipset also supports memory asynchronous work mode, such as Intel910GL chipset, only MHZFSB support 533 or 133 MHZ of CPU by, but it can match work frequency for 133 MHZ of DDR266, working frequency for 166 MHZ of DDR333 and working frequency for hp pavilion dv5-1004el laptop cpu fan 200 MHZ DDR400 of normal work (note at the CPU by 133 MHZ and DDR400 work frequency 200 MHZ has differ 66 MHZ), only tie-in and different memory its performance have differences sake. Again, the CPU overclocking, in order not to make memory tow CPU overclocking ability of the hind leg, right now can turn down memory work frequency so that YuChaoPin, for example, AMD Socket939 interface Opteron144 very easy to overclocking, many products outer frequency can easily exceed 300 MHZ, and this if the memory synchronous work mode, the memory of the equivalent frequency will be as high as DDR600, this is obviously not possible, in order to smooth over 300 MHZ external clock, we can in overclocking before the mortherboard BIOS memory set to DDR333 or DDR266, in excess of 300 MHZ external clock after, the former also however just DDR500 (some acura memory can achieve), while the latter is only DDR400 (completely is normal standard frequency), thus it can be seen, the correct Settings memory asynchronous mode helps to overclocking success.
 
The mainboard chipset almost all support memory asynchronous,hp pavilion dv5-1004nr laptop cpu fan Intel company from 810 to the current series of relatively new series 875, support, and via the company from 693 after all chipset provides this function.



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