Everything You Always Wanted to Know About SDRAM (Memory): But Were Afraid to Askby Rajinder Gill on August 15, 2010 10:59 PM EST
It’s coming up on a year since we published our last memory review; possibly the longest hiatus this section of the site has ever seen. To be honest, the reason we’ve refrained from posting much of anything is because things haven’t changed all that much over the last year – barring a necessary shift towards low-voltage oriented ICs (~1.30V to ~1.50V) from the likes of Elpida and PSC. Parts of these types will eventually become the norm as memory controllers based on smaller and smaller process technology, like Intel’s 32nm Gulftown, gain traction in the market.
While voltage requirements have changed for the better, factors relating to important memory timings like CL and tRCD haven’t seen an improvement; we’re almost at the same point we were a year ago. Back then Elpida provided a glimpse of promise with their Hyper-series of ICs. The Hyper part was capable of high-speed, low-latency operation in tandem. Unfortunately, due to problems with long-term reliability, Hyper is now defunct. Corsair and perhaps Mushkin still have enough stock to sell for a while, but once it's gone, that’s it.
The superseding Elpida BBSE variant ICs and a spread of chips from PSC now dominate the memory scene, ranging from mainstream DDR3-1333 speeds all the way to insanely-rated premium DDR3-2500 kits. Some of these parts are capable of keeping up with Hyper when it comes to CL, but do so by adding a few nanoseconds of random access latency due to a looser tRCD. Given that read and write access operations make up a significant portion of memory power consumption, this step backwards in performance may be a requisite factor for reliability – perhaps something was found by Elpida during the production lifetime of Hyper ICs that prompted a re-examination, leading to a more conservative recipe for data transfer/retrieval.
Today’s memory section comeback was fuelled by the arrival of a number of mainstream memory kits at our test labs – many of the kits we were using for motherboard reviews are no longer for sale so we needed to update our inventory of modules anyway. Corsair, Crucial and GSkill kindly sent memory from their mainstream line-ups. The original intent was to look at a few of those kits.
However, during the course of testing these kits, our focus shifted from writing a memory review (showing the same old boring graphs) to compiling something far more meaningful: a guide to memory optimization and addressing, including a detailed look at important memory timings, and an accounting of some of Intel’s lesser-known memory controller features. As such, this article should make a very compelling read for those of you interested in learning more about some of the design and engineering that goes into making memory work, and how a little understanding can go a long way when looking for creative ways to improve memory performance…
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mupilot - Monday, August 16, 2010 - linkNice article, its very in depth, but easy to read! I'll have to read through a couple times if I truly want to understand how my memory works so I can actually understand what I'm doing when I overclock my memory and adjust the timings.
Cool Mike - Monday, August 16, 2010 - linkI find memory a bit confusing. What type of memory would be best (or even work) on an AMD system - for example the Asus M4N98TD EVO. Will the lower voltage modules work? I'd like to get some pretty decent memory, but almost all of the discussions are around Intel based chipsets. Any help would be appreciated.
vajm1234 - Monday, August 16, 2010 - link---- well i too wanna see a comparison how AMD works against the intel
PrinceGaz - Monday, August 16, 2010 - linkWhilst the text for the Mistake Counter is incorrect, the bit count in the table does match the text-- the PARAMS2 register holds the 9, not 8 MSBs of each parameter (the internal values being 13 bit, not 12 bit), and the text and diagram both agree on this.
PrinceGaz - Monday, August 16, 2010 - linkOh and by the way, thankyou for an extremely informative article which has refreshed (hehe) and added to what I knew about how RAM operates and the effects of the main timings.
Icepop66 - Monday, August 16, 2010 - linkThanks for touching on some of the important aspects of sdram architecture and function and how they're related. My understanding is better now. Thanks for consistently good articles and reviews.
Gary Key - Monday, August 16, 2010 - linkRampage III Extreme -
BIOS 0878 -
1. Opened Memory Timing Selections for Ultimate Tweaking
2. General Performance Enhancements for Overclocking
3. AnandTech Memory Article BIOS - Support provided by ASUS USA Tech Support (that would be me).
lowenz - Monday, August 16, 2010 - linkSimply AWESOME article!
Muhammed - Monday, August 16, 2010 - linkYou didn't mention the fact that (for example) DDR3 1600MHz actually works @200 MHz , and by fetching 8-bits per clock , it can effectively work like a 1600MHz RAM .
DDR2 @800 MHz , actually works at 200MHz too but fetching 4-bits per clock .
DDR@400 MHz , actually works at 200MHz too , fetching 2-bits per clock .
MrBrownSound - Monday, August 16, 2010 - linkThank you for helping me understand. Yes I was afraid to ask, or maybe I just felt I didn't need to know. I was wrong.