RAM Timings?

[idissectgirls]

I am looking for a very detailed explanation of DDR ram timings, more specificaly, Corsair Twinx PC3200 512MB (2x256 Dual DDR). I have built an awesome system from all new hardware...well almost new...see signature. I am completely happy with the way my PENTIUM system is running. I just want to know what the hell the four numbers for ram timing mean! For example: my corsair ram is running at 2-3-3-6. What does each number mean? I have read about the first number "2." It has something to do with latency and 2 is the lowest possible number for todays ram. Thas nice woo-hoo...and I have read something about the last number "6." It has something to do with bursts and clock cycles. I am not exactly sure what relationship the last number represents. Now the two middle numbers "3" and "3" are a total mystery to me. I would like someone to explain all the numbers to me in a very detailed manor...and any other useful ram information. Thank you for your time.

[AllGamer]

not always the best RAM will yield the best results

you'll have to check your mobos settings too

what Mobo do you have?

[idissectgirls]

I have an Abit IC7-G...I'm sure that Corsair dual ddr was my best choice...now what do you know about ram timings?

[$1500-P4 gamer]

"now what do you know about ram timings?"

Try google.
:x
"Ram timing guides" you'll find 100's of'em. No sense in retypeing what other have a million times before.;)

[idissectgirls]

I used google...I didnt find anything. That's why I wrote in here. Now, what do you know about ram timings?:r

[idissectgirls]

You said "Try Google 'Ram timing guides' you'll find 100's of'em."

Well that was a good idea, I know that whenever I want to learn something new I go to google, I even go to google when I want to just browse around on the net. Actually google is my homepage. I love google!

Now, just to show you how hard this stuff is to find, here is your suggestion in the form of a link (http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=Ram+timing+guides&btnG=Google+Search). The most obvious choice on that page is the Tom's Hardware Guide links, but they don't yield anthing more useful than an explanation of latency. The rest of the next 5 pages is filled with junk.

I would like to know what each number in the ram timing sequence 2-3-3-6 mean. The more detail the better.
Thank you to anyone who replies with something usefull to say.

[ichorid]

corsair explains (http://www.corsairmicro.com/memory_basics/153707/index.html)

it applies to all ram tho, not just corsair

[Terminator]

Here's maybe an oversimplified desciption but might shine some light on it:-

Example of a CAS 2-2-2-5-1T DDR DRAM chip

First value 2 = CAS latency: 2.0 clock cycles
Second value 2 = RAS-to-CAS delay: 2 cycles
Third value 2 = RAS precharge: 2 cycles
Fourth value 5 = RAS active to precharge: 5 cycles
Fifth value 1T = Command rate: 1T (1 cycle)

CAS = Column Address Strobe
RAS = Row Address Strobe

Fourth value 5 is sometimes called the Dram leadoff timing and high because the address must first be initialised.

Values 1,2 and 3 are normally referred to as Burst cycles.

In general the lower the values the better performance but possible instabilities but sure you know this.

T

:t

[$1500-P4 gamer]

"Thank you to anyone who replies with something usefull to say"

"Corsair dual ddr was my best choice...now what do you know about ram timings?"


"That's why I wrote in here. Now, what do you know about ram timings?"

I dont know if its just how the text is reading-but I dont think I like yer attitude.
:p

[$1500-P4 gamer]

One of those useless google results you overlooked...:rolleyes:

http://www.radiativenz.com/guides/memoryguide/index3.shtml
"RAM is immensely complex, and there are dozens of other timings and optimisations, though very few of these can ever be set by the end user. The only other two you’re likely to cross are the RAS delay and possibly one or two other latencies.. RAS is normally 6 clock cycles, but can be shortened to 5.

Command rate is the next most common delay. It can be set to either 1T or 2T. 2T is standard, and 1T a little faster. Another option you might come across is Row Cycle Time (Trc), which can be set to 3 or 2. You may also see RAS precharge (set to 2 or 3) and Leadoff Command (set to 3 or 4).

Other timings associated with memory include (but are certainly not limited to):

Bank Active Time
Bank Cycle Time
Data-In to Precharge
Data-In to Active
Bank-to-Bank Delay

...and so forth. Most of these timings will be set hard by the manufacturer of the RAM, and are normally pretty similar within memory types (eg: PC2100 DDR, PC800 RAMBUS, PC133 SDR etc), so there’s normally no reason to worry about these.

The RAS delay is obviously less important than the CAS delay due to it’s relative infrequency. There is also a small delay between the memory’s charging of the correct column and its charging of the correct row. This delay is the RAS to CAS delay (CMD), and it occurs with every row access. While these timings have a much lesser effect on performance, the fact that combined you can shave off 2 clock cycles from a memory read is enough to warrant at least trying them.

Memory is accessed via a sequence of readying steps. Both the column and the row to be addressed must be readied before they can be read or written. Even if the row is charged, if the column isn’t, then the memory cannot be read from or written to. Once the data is available, it is sent along the memory bus towards the CPU (or possibly the video card if you’re using side-band addressing) on the next clock cycle.

Registered or buffered RAM has an extra step to all of the above. In order to synchronise the timings (especially important with many memory modules all run in high Interleave modes), data is first put into some registers (hence the name registered) before being output. This ensures that all data sent out is synchronised properly, eliminating a lot of memory errors. This step takes one clock cycle, so CAS 2 registered RAM will perform like CAS 3 unbuffered RAM (only it is less likely to suffer errors)."


Lots more there too. Like I said try searching google once.

;) :t

[Terminator]

Hi $1500-P4 gamer

errrrr When I read the reply I thought this was a bad attitude as well and for someone new not exactly how to go about getting 'useful' advise.

I put the answer over simply but I knew that there was a heap more to RAM timings/synching/etc than the 5 numbers.

Floopy disks at 3 paces I think.... :r nah don't bother....argueing here is not worth the effort.

T

:t

[Rocketmech]

Are you really,really sure you want to know, Grasshopper?

All the links are provided thru Google. :rolleyes:

Read it all , if you have questions afterwards , comeback here and bring a spoon. ;)

http://www.dewassoc.com/performance/memory/memory_speeds.htm

http://www.techwarelabs.com/reviews/memory/memory_timings/

http://www.rojakpot.com/default.aspx?location=4&var1=117

http://www.arstechnica.com/guide/building/bios/bios-1.html

http://www5.sharkyextreme.com/hardware/memory_guide/

http://tweakhomepc.virtualave.net/ram/rambios.html


:t

[$1500-P4 gamer]

Gonna need some asprin after all that reading!;)

[idissectgirls]

Thank you everyone!!! The ram timing information has soaked in. There was so much information, I think I might have forgotten a few things in order to learn so much...like tying my shoe. Now I know, why people were velcro shoes...they just learned about ram timing. Well I'm off...to Shoe Carnival.

Thanks again!!

ps. P4 Gamer, I was very frustrated when you say I had a bad attitude...I did. I'm sorry Gamer, and I'm sorry to everyone else who read that.

pss. Maybe you guys can help me with my next post...It's about Windows Media Center Edition...I'm not sure where it will be, but the forums are logically laid out...see you there.