The New Mainstream Standard?
The portfolio of DDR3 speeds has opened up far sooner than it had for DDR2, as DDR3 data rates of 1066, 1333 and 1600 MHz have all appeared within the past few moths to replace DDR2’s 533-, 667-, and 800-MHz data rates. As with DDR2, higher "nonstandard" speeds are also available, but standard speeds are what most buyers need to be familiar with.
Today, we bring you what should have eventually become the "mainstream choice" of DDR3 speeds, as its 1333-MHz data rate falls between the "low-cost" and "high-performance" 1066 MHz and 1600 MHz standards that fill the spectrum. A total of 13 top brands were invited to participate, and eight were able to respond with a total of ten kits for your consideration.
As with most of our shootouts, we pushed each kit to the edge of stability to find its ultimate performance, but before we move to the test results, let’s consider the market for DDR3. What advantages does it have over DDR2? Why was it introduced? And when new technology comes at a price premium, who should buy it?
What’s In A Name?
The "official" name for DDR memory is based on its bandwidth rather than clock speed. The easy method to convert data rate to bandwidth is to multiply by eight. Thus, DDR-400 is called PC-3200; DDR2-800 is called PC2-6400 and DDR3-1600 is called PC2-12800.
The math behind this conversion factor is simple: PC memory modules based on SDRAM technology use a 64-bit connection; there are eight bits in a byte and 64 bits equal eight bytes. For example, DDR2-800 transfers 800 megabits per pathway per second; its 64 pathways provide one eight-byte transfer per cycle and 800 times eight is 6400.
The problem comes with "rounding" and was first noticed with DDR-266 (PC-2100). The data rate of 266 MHz is actually 266.6 (continuously repeating decimal) megahertz, so the true transfer rate was 2133MHz.
Today’s DDR3-1333 has a peak bandwidth of 10666 MHz, which can be improperly rounded down and called PC3-10600, rounded up to be called PC3-10700 or stated without rounding as PC3-10666 depending on the manufacturer’s desires.
Buyers will find that searching some vendors for multiple DDR3-1333 brands will require them to check all three "ratings" to view modules of the same actual speed, but most brands label their DDR3-1333 products as either PC3-10600 or PC3-10666.
- Next page Tomorrow's Bandwidth...Today!
One part on page 3 is a bit confusing to me:
"Because cycle time is the inverse of clock speed (1/2 of DDR data rates), the DDR-333 reference clock cycled every six nanoseconds, DDR2-667 every three nanoseconds and DDR3-1333 every 1.5 nanoseconds. Latency is measured in clock cycles, and two 6ns cycles occur in the same time as four 3ns cycles or eight 1.5ns cycles. If you still have your doubts, do the math!"
If I am reading this right, cycle time is the inverse of (1/2)*(DDR Data Rate or 333 for example). So 1/((1/2)*333)=.006006006 which rounds to 6 milli-seconds, not 6 nano-seconds.
Sorry for my confusion, but could someone please clarify for me?
I can not clarify...this is a good article, but im still anoyed at the spelling and punctuation in the articles...Im not one for utmost spelling and punction in informall chatting messaging etc (like this) but i am when its a published article, you wouldnt find a harry potter novel with spelling mistakes in it....
"and DDR3-1600 is called PC2-12800." Its surposed to say, PC3-12800 not...PC2-12800
On the first page mid way down ^^^
Therlian you got it wrong. Generally, period (cycle time) it's the inverse of frequency (clock speed). But as DDR stands for Dual Data Rate, its real frequency is 1/2 of the specified clock speed. What you did wrong it's that you didn't take in account that DDR-333 means a data rate of 333 MEGA-hertz. Because a hertz is the inverse of a second you get: 1/((1/2)*333 MHz)=.006 micro- seconds, which is equal to 6 nano-seconds. Hope I made it clear for you.
I see now danmari. Thanks for pointing that out. I don't know why I didn't think about the 333 being MHz as opposed to Hz.
"I can not clarify...this is a good article, but im still anoyed at the spelling and punctuation in the articles...Im not one for utmost spelling and punction in informall chatting messaging etc (like this) but i am when its a published article, you wouldnt find a harry potter novel with spelling mistakes in it...."
Sorry but when you make THAT many mistakes in your own post, you have no right to talk about spelling mistakes. The mistake you mention is a typo (hitting a wrong key) not a spelling error.
You however manage to spell "annoyed", "informal", and "supposed" wrongly. You also managed to spell "punctuation" wrongly (the second time.. not sure how you can spell it right the first time and wrong the second..)
If you don't know how to spell, then don't flame others for it.
anyone with notes PC2100,PC3200,PC4200,PC5300?