View Full Version : DDR vs RDRAM

2003-04-02, 03:29 PM
Didn't see this posted yet so....

Which is better? Or should I rephrase...Which do you prefer and why?

As stated in another post, I'm getting a new computer, and need to decide whether to go with RDRAM or DDR.

Any comments?

2003-04-02, 04:29 PM
well considering Rdram is for p4's and cost an ass load of money. I prefer ddr...

of course If you are going to get a good p4 might as well get the rdram so your FSB matches the RAM speed.

bah, I hate pentiums... so damn expensive and the ends don't justify the means...

2003-04-02, 04:53 PM
Here's most of the argument of DDR vs. RDRAM (RAMBUS) right in a simple
chart. (the one at the top of the page)


Basically, RAMBUS used to be faster and have higher bandwidth. From what I
gather, they got such high clock speeds (600Mhz) because they used a 32 bit
bus and split it to 2 x 16 bit buses allowing them to access different
places in RAM more easily. Multiply in the crazy clock rate and you have
pretty big bandwidth. The thing is, when you have a 64 bit bus vs an
effective 32 bit bus (2 x 16) you can see you only need half the clock rate
in DDR to equal the bandwidth of RDRAM. Since DDR was cheaper it evolved
faster and outpaced RDRAM.

At the moment, DDR2 (dual) is a 64 bit bus at a speed of 200Mhz giving much
higher bandwidths than RDRAM.

Bandwidth is the important factor, not clock rate. Even original DDR got
pretty close to the bandwidth of most types of RDRAM and since it cost half
as much, its a no-brainer for most people what is "better". RDRAM used to
have higher bandwidth than DDR, but not anymore.

And yes, DDR is cheaper for the same bandwidth:
$26 - PC2100 DDR 256MB
$42 - RDRAM 1066MHz 128MB x2 = $84

Those are the lowest prices(for non-generic RAM) from www.pricewatch.com and those modules have the same bandwidth.

So, in short, I prefer DDR since it's a lot more bang for the buck.

[Edit:] Note, I'm refering to single channel RAM in the above post.
If you are getting a dual channel board, the same still applies just the bandwidth for each type of RAM on a dual channel board would be doubled.
So still, with dual channel, DDR = win ;)

2003-04-02, 09:54 PM
Hey hunter thanks for the great reply. I'll most likely be looking into DDR Ram.
Thanks again!

2003-04-02, 11:32 PM
Your welcome :cool:

2003-04-03, 04:36 AM
Just so ya know, intel has given up on RDR aswell... The new replacementboard for the 85x series is the granitebay chipset and that uses dual band DDR.

As for RDR matching the bus speed, thats not entirely true, RDR used a real bus of 200mhz, p4 uses 133 or 100... Thats why the granitebay uses 133mhz chips..

But the new 200mhz fsb p4's will be using 200mhz ddr chips... can't wait for those =)

*note, the bus speeds i've listed are the "real" speeds, whitout the double data rate or quadtech.