SDRAM, DDR, RDRAM

efript

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Jun 20, 2002
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Ok so sdram runs at 100 and 133 mhz, ddr at 200, 266, and 333, and rdram at 600 and 1000+. Correct? Is rdram like unbelievably fast? or is the difference barely noticable?
 

BigBiggist

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SDRAM does run at 100 and 133. DDR Ram actually runs at 100, 133, 166, and 200 but it completes two clocks per cycle, not one like sdram, thus giveing it the 200, 266, 333, and 400 ratings. RDRAM runs at 400 and 533. DDR 333 is slightly faster than PC-800 (400Mhz). DDR 400 and PC-1066(533 mhz) perform almost identically. DDR 400 might be a little bit faster in some areas and the PC-1066 in others. You wouldn't notice the differences though. I don't know much about RDRAM or Rambus. It may also complete two clocks per cycle to get the 800 and 1066 ratings but Im not sure. The only way you will really notice the differences is if you compare PC-133 to something like DDR 400 or PC-1066.

I will try to find a article that explains it better than i can.

Hope I was some help.
 

efript

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k im looking at the different types of ddr. they have 1600, 2100, 3000, 3200, and 3500. how much of a difference will one notice from say the 2100 and the 3500?
 

Crashman

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The first guy has some ideas, some are even right. DDR200 is 100MHz and called PC1600. DDR266 is 133MHz and called PC2100. DDR333 is 166MHz and called PC2700. DDR400 is 200MHz and called PC3200.

Now, Rambus is also DDR, PC800 runs at 400MHz and PC1066 runs at 533MHz. PC800 is exactly the same bandwidth as PC3200. PC1066 has no equal.

Because Rambus responds a little slower than DDR SDRAM, PC800 beats DDR333 only by a small margin. DDR400 beats PC800 by a small margin. And PC1066 beats DDR400 by a slightly larger margin.

The best possible performance comes from running PC1066 at 600MHz, by increasing your front side bus to 150MHz. Kingston PC1066 has fast enough chips to allow that overclock. There is no DDR SDRAM on the market that even comes close.

<font color=blue>By now you're probably wishing you had asked more questions first!</font color=blue>
 

Crashman

Polypheme
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There is no legitimate PC3500. The stuff you see on the market is overclocked, and must be run at much higher voltages than stock. Even then, it's not very reliable at that speed. Since your previous question included Rambus, I assume you're looking into a P4? The best board for the P4 right now is the Gigabyte GA-8IHXP, which takes RDRAM. Your best overclocking CPU is the 1.6A. At 150MHz system bus, the 1.6A will run 2400MHz, the RDRAM will run at 600MHz "PC1200" speed, and you'll leave stock P4 2.4's far behind.

<font color=blue>By now you're probably wishing you had asked more questions first!</font color=blue>
 
Damn! While I was working out the answer, you answered.

Anyway, I'll post this up as a reference. If it's not quite right let me know.

SDRAM:

PC66 = 66MHz FSB
PC100 = 100MHz FSB
PC133 = 133MHz FSB

DDR RAM:

PC-1600 = DDR 200 = 100MHz FSB
PC-2100 = DDR 266 = 133MHz FSB
PC-2700 = DDR 333 = 167MHz FSB
PC-3000 = DDR 366 = 188MHz FSB
PC-3200 = DDR 400 = 200MHz FSB
PC-3500 = DDR 433 = 216MHz FSB

RD RAM:

PC-600 = 300Mhz Memory Bus = 75MHz FSB???
PC-700 = 350MHz Memory Bus = 88MHz FSB???
PC-800 = 400MHz Memory Bus = 100MHz FSB
PC-1066 = 533MHz Memory Bus = 133MHz FSB

Cheers Crash.

<b><font color=blue>~ Gotta question? Tried searching the boards first? Good! Ask away! ~<font color=blue></b> :wink:
 

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