# Thread: ddr2 clockspeeds and module names explained

1. ## ddr2 clockspeeds and module names explained

its getting a little confusing with all those pc5200 and DDR2 675 names, i hope this helps to answer some questions and make some of you that wonder about those numbers understand what they mean

sdr sends one bit at every clock
ddr sends one bit at the rising and the falling of each clockcycle wich means it has twice the bandwidth at the same clockspeed (in theory)
ddr2 uses 2 groups of memory chips wich get a different reference clock, the reference clock for one group of the chips is shifted from the clock signal the other group gets, this means if each memory chip is running at 100mhz the bandwidth of the memory configuration wich the two groups working with a shifted reference clock is twice as high as if all chips would use the same reference clock. since the chips also send a bit at the rising and falling of each clockcycle we get 4 times the bandwidth at the same clockspeed (in theory)

name of the memory - speed the chips are clocked at - speed the memory modules are clocked at - speed the modules communicate with the chipset at - marketing name based on the claimed theoretical max bandwidth in mb/s

red = unofficial speed rating wich isnt a set standard by jedec

sdr 100 = 100mhz internal speed = 100mhz external speed = 100mhz SDR = pc100
sdr 133 = 133mhz internal speed = 133mhz external speed = 133mhz SDR = pc133
sdr 150 = 150mhz internal speed = 150mhz external speed = 150mhz SDR = pc150

ddr 200 = 100mhz internal speed = 100mhz external speed = 200mhz DDR = pc1600
ddr 266 = 133mhz internal speed = 133mhz external speed = 266mhz DDR = pc2100
ddr 300 = 150mhz internal speed = 150mhz external speed = 300mhz DDR = pc2400
ddr 333 = 166mhz internal speed = 166mhz external speed = 333mhz DDR = pc2700
ddr 375 = 187mhz internal speed = 187mhz external speed = 375mhz DDR = pc3000
ddr 400 = 200mhz internal speed = 200mhz external speed = 400mhz DDR = pc3200
ddr 433 = 216mhz internal speed = 216mhz external speed = 433mhz DDR = pc3500
ddr 466 = 233mhz internal speed = 233mhz external speed = 433mhz DDR = pc3700
ddr 500 = 250mhz internal speed = 250mhz external speed = 500mhz DDR = pc4000
ddr 533 = 266mhz internal speed = 266mhz external speed = 533mhz DDR = pc4200
ddr 566 = 287mhz internal speed = 287mhz external speed = 566mhz DDR = pc4500?
ddr 600 = 300mhz internal speed = 300mhz external speed = 600mhz DDR = pc4800

ddr2 400 = 100mhz internal speed = 200mhz external speed = 400mhz DDR = pc2-3200
ddr2 533 = 133mhz internal speed = 266mhz external speed = 533mhz DDR = pc2-4200
ddr2 667 = 166mhz internal speed = 333mhz external speed = 667mhz DDR = pc2-5300
ddr2 800 = 200mhz internal speed = 400mhz external speed = 800mhz DDR = pc2-6400
ddr2 933 = 233mhz internal speed = 466mhz external speed = 933mhz DDR = pc2-7500
ddr2 1000 = 250mhz internal speed = 500mhz external speed = 1000mhz DDR = pc2-8000

ddr2 1066 = 266mhz internal speed = 533mhz external speed = 1066mhz DDR = pc2-8600

please correct me if im wrong

2. thanks Saaya, I tihnk this should help out more people upgrading their intel rigs.

3. DDR200=PC1600
DDR266=PC2100
DDR333=PC2700
DDR400=PC3200
DDR433=PC3500
DDR466=PC3700
DDR500=PC4000
DDR533=PC4200
DDR566=PC4400?
DDR600=PC4800

jjcom

4. Here's a rule of thumb for ya Saaya...

DDR500 = PC4000

So: take the "DDR" figure & multiply it by 8... or vice versa, take the "PC" figure and divide it by 8

5. nice one saaya

according to ocz:
ddr2 at 800Mhz is PC2-6400
and ddr2 at 1000mhz is PC2-8000

6. thx jesse rabbi and funny_s

about ddr2 ratings its still confusing me why it got a bump of only 1000 on the rating from 100 to 133 chip clockspeed

memory chip clockspeed - rating - increase over previous rating

100 3200
133 4200 1000
166 5300 1100
200 6400 1100
233 7500? 1100?
250 8000 500
266 8600? 1100?

and is ddr933 an official jedec rating or not? i havent heard about it yet...
i guess it doesnt exist as intel went from 200fsb to 266fsb?
but then again pc8600 doesnt run in 1:1 with 266fs as its clocked at 533mhz externally

7. You have 2 DDR400's in the list, one red, one black. The second one shouldnt be red.

8. Originally Posted by saaya
[COLOR=Red]ddr2 933 = 233mhz internal speed = 466mhz external speed = 800mhz DDR = pc2-7500
DDR2 933=233mhz internal speed=466mhz external speed=933mhz DDR=PC2-7500

DDR375=PC3000

jjcom

9. This how DDRII basicly works?

Or is it like

10. thx for pointing out the typos guys

dippsy, i dont get what you mean... sorry...
check lostcircuits, they have a great guide explaining ddr2

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