[Elbatrop1's Guide to RAM] -
Elbatrop1's Guide to RAM
Discuss Elbatrop1's Guide to RAM
Posted by: Elbatrop1
There are sooo many different types of RAM out now. But, what I'll do is give a basic break down of the types that are common for computers today:D
[b]SDR SDRAM (Single Data Rate Synchronous Dynamic Random Access Memory)[/b]
SDR SDRAM isnt used anymore for new computers, instead it was used for slightly older computers (PIIs, PIIIs). The RAM stick itself has 168 pins. Common speeds that are found for SDR SDRAM were PC100 and PC133, meaning that it is matched to a CPU with a 100MHz or with a 133MHz FSB.
This RAM technology is obsolete now, and prices have skyrocketed.
[b]DDR SDRAM (Double Data Rate Synchronous Dynamic RAM)[/b]
This is the standard today for new AMD computers. New Intel's have done away and favored for DDR2. DDR uses 184 pins.
The most common speed for DDR is PC3200, with other common speeds being PC2100 and PC2700. Unlike SDR, DDR's PC number corresponds to the bandwidth it provides rather than the actual frequency the chips run at. This means that PC3200 provides bandwidth of 3200 MB/s.
The frequency that the chip runs at is "DDR 400" or 200MHz. Since DDR RAM transfers data twice for every clock cycle (1MHz), it is considered to have a DDR frequency double that of its actual running frequency.
[b]DDR2 SDRAM[/b]
DDR2 is currently the standard for new Intel computers. DDR2 is important for Intel because it can supply a lot of bandwidth to their frequency-intensive CPUs.
DDR2 has a lot in common with DDR, but I'll start with the differences. DDR2 now has 240 pins. DDR2 more commonly runs at higher frequencies than DDR does. The higher frequencies are due to an improved electrical interface, on-die termination, prefetch buffers and off chip drivers (thanks wikipedia).
One problem that has come with making DDR2, is latency. Although the speed that the chips can sustain is higher, high latency has hindered its performance a little.
Common speeds of DDR2 are PC2 3200 (DDR2 400), PC2 4200/4300 (DDR2 533), and PC2 5300/5400 (DDR2 667).
[b]Dual Channel[/b]
First off, dual channel is not a particular type of RAM. DC is a feature that comes with chipsets (and therefore motherboards). Currently, the more popular sockets support dual channel. AMD's skt939 and AM2 support DC. As well, Intel's skt478 and 775 support DC.
To run RAM in dual channel configuration, you need 2 sticks that are similar or 4 sticks that have similar pairs. When deciding to go with DC, you should get RAM that is identical, as to prevent any problems. However, you can often run non-identical RAM in dual channel. The pair of RAM sticks must be the same size (1GB, 512MB, etc).
Dual channel doesn't give a large performance increase. Overall, it gives about a 1-4% increase in performance.
[b]Other[/b]
There are other types of memory available today like RDRAM, but it isnt very common, and pretty expensive.
Hope that helps:D
If anyone has anything to add, then I'll edit it in. I'm gonna try to get this stickied. I would especially like it if someone wrote up something for latencies:D
Posted by: DoomUK
Good work Elbatrop1, this should be put up as a sticky.
Posted by: gaara
May want to add DDR3, GDDR and it's many counterparts, RD RAM, and XDR RAM. There's so many different platforms out there
Posted by: Elbatrop1
Hmmm. I was going for the more common types out there, that can be upgraded, added, etc.
gaara, you probably know the ones you listed as well as the back of your hand, perhaps you should give some info ;) :D
Posted by: Trifid
Great work there Elbatrop. :p
Well GDDR3 should be added, as it is now used in the GPU's. (Always wondered what the differnce is between GDDR3 and DDR3....)
Even though it should be a sticky, there are too many stickies. there should be a Elbatrop's guides in one.
There is also PC8000 for the DDR2, god thats fast...
Posted by: Qiranworms
Stickied...
Yes, we have a lot of stickies in hardware. But realize that things are going to be moved around and everything should end up more usable soon enough ;).
Posted by: Elbatrop1
[quote]Even though it should be a sticky, there are too many stickies. there should be a Elbatrop's guides in one. [/quote]
Haha, I agree! There is a lot of stickies. Perhaps there should be a special sub-forum especially for my guides, etc ;) :D jk
Posted by: Chankama
The best thing to do with respect to guides is to go somewhere like wikipedia.org and add a page - if it doesn't exist. I've modified some pages myself. And then, you can just have one single thread that will have a link to all these "guides".
There's a pretty good collection, at the popular science level, of many topics on wikipedia.. :)
Posted by: nitestick
perhaps a new sub-forum for general guides? good work elbatrop1. maybe you should add EDO and FPM hahahaha.
Posted by: neosnightmare
good listing there. i would be interested in the GDDR though but that's simply because i was looking into it a while ago.
Posted by: MattRiddle
How do you know what type of RAM your computer needs?
Posted by: nitestick
your motherboard manual is the simplest way to find out. if you need help post some more info. you can use programs to identify the type of RAM (in a systerm that already has RAM or look at the type of RAM already in it.
Posted by: Sh0r_ty
just might want to note that although PC3200 Should have 3.2gps bandwidth some pc3200 can be as low as 2.4-5gps bandwidth
Posted by: Madmonk325
mmmmm.... ram, ram, ram..... i love ram.... even tho i dont have enough. lol
Posted by: Unregistered67
Good thinking
Posted by: Camden
Is there even any one of those that's waaaay ahead of the pack qualitywise?
Posted by: bonehelm
can i have two different brands of ram in the rig?
Posted by: nitestick
yes, it only matters when it comes to more specific things like trying to run dual channel. there are a few brands that stand out. OCZ being my preference. as a rule you get what you pay for basically.
Posted by: lamedog
Hi
Your info's good for those who want some basic knowledge but I am a bit confused why you don't include RD Ram as a common type of ram. Yes it is more for servers and it does not really concern the basic user but it can be used in a desktop system aswell.
You must know that RD Ram has been around for some time and most IBM servers and other servers will have that type of ram for their systems but have your ever wondered or looked at the possibility of getting a AMD opertron or Xeon based system instead of a Althon64 X2 etc etc. I know I have including ideas of the possibility of an dual Octo core computer. The Octo (8) is based on Intel's latest predictions of the up and coming lines coming out of their production runs. Octo cores should be here by 2008.
Sorry to get sidetracked. RD Ram against a DDR2 667mhz computer would be quite interesting. Some high performance gaming computers have become in essence a server geared for gaming. Some even have dual or custom water cooling systems for dual core dual processor systems.
Just thought I'd add these comments for you guys to think about.
Kind Regards
lamedog
Posted by: Apokalipse
[QUOTE][i]Originally posted by lamedog [/i]
[B]Your info's good for those who want some basic knowledge but I am a bit confused why you don't include RD Ram as a common type of ram. [/B][/QUOTE]well, it really isn't a common type of RAM.
Intel tried to push people to RD when they made their Pentium 4's (RDRAM is the reason the Pentium 4's FSB is quad pumped) however DDR was (and still is) a lot less expensive, and performance not much less, especially with dual channel.
it didn't grow into the market very much, and just faded away.
Posted by: Elbatrop1
Updated to include Dual Channel information July 5 2006 :D