View Full Version : [OT] RAM Lesson
I am building a computer for the first time and am in the process of getting the correct RAM. I want 1 gig. I want to get PC-3200 so I can overclock. I am getting a ASUS ASU-A7N8X DELUEX RETAIL Motherboard. I am getting a AMD Athlon XP 2500+ (Barton) 333 FSB 512K.
I went to Kingston webpage and chose the exact m/b from the campatibility list and found this was my choice.... Link to the Datasheet for the RAM module....
http://www.valueram.com/datasheets/KVR400X64C25_512.pdf
This RAM is listed at $115 for 512MB
So I was looking around and found a different Model of PC-3200 Kingston 512MB for only $85. The link to its datasheet...
http://www.valueram.com/datasheets/KVR400X64C3_512.pdf
The only difference in the names are that the $115 is C25 and the $85 is C3. I don't know what this means.
Can someone take a look at the specifications of these two types of RAM and tell me what the difference is? Can go with the cheaper version even though it didnt come up on the list of compatible RAM for my specific motherboard? Is that list of 'compatible RAM' just a list of what Kingston wants you to buy for your motherboard even though you have other cheaper options?
Thanks...
It's referring to column access strobe latency (sometimes known as CL, or CAS).
The number is the number of clock cycles it takes to address a given column in the DRAMs.
So C2 = 2 cycles before column accessed, C3= 3 cycles before column accessed etc.
Therefore lower is better/faster ... *but* the real world results depend heavily on how good your system board's ram timing is, and CAS isn't the only DRAM feature that affects timing, so a given module might be better in one area, but worse in another.
As far as memory pricing goes ... the general rule of thumb is that faster = more expensive, but that's only true for current, easily available modules.
It's a very fast turnover time sensitive commodity market, so you can sometimes pay a premium for slightly older stuff that's not in the current high volume supply pipelines.
Can someone give me an opinion on which RAM I should choose. I want the RAM to be compatible and fast but I dont want to pay $30 more per 512 if I don't have to.
get the appropiate ram speed for you mb and choose a quality brand.
The CL will sometimes help other times not. i dont spend that much time worrying on my rams cas latency.
In genral id rather buy more than faster ( wgen talking CL i mean, always get the optimum speed for you MB/cpu IE ddr 333 and such) ram.
I have the same mobo you are planning on buying, and aside from my current problems (see here (http://neocron.jafc.de/showthread.php?s=&threadid=81417):(), I love it.
Since you are planning on buying the XP2500+ with a 333MHz FSB, I would suggest getting Corsair TWINX1024-LL or LLPT (http://www.corsairmicro.com/corsair/products/specs/twinx1024-2700ll.pdf) (<-- .pdf) Dual Channel DDR PC2700, also the RAM I use. It has low CL which is a benefit of using dual channel RAM.
The reason I suggest the PC2700 instead of the PC3200 is that, from my research, it is better for stability, even when OC'ing, to run your RAM at the same speed as your CPU FSB. Not entirely sure though. Maybe someone can comment if I am wrong.
If you plan to OC your system, I would strongly suggest getting RAM designed to be OC'ed too. The only problem with that is it's expensive.
I bought my RAM at newegg.com and spent something like $268 at the time.
Anyway, just thought I'd share some of my experience and research I learned from building my current system.
I hope I was able to help or at least offer some food for thought.
/edit - if you do go with PC3200 make sure you check Asus' QVL Table (http://usa.asus.com/prog/spec.asp?m=A7N8X%20Deluxe&langs=09) before buying it. Asus is extremely picky when it comes to compatability.
Mushkin's (http://www.mushkin.com/) also a good brand to look at, although they are a bit pricey. They also have their own DDR motherboard compatability list (http://www.mushkin.com/epages/Mushkin.storefront/3fb048b903d2febc273fc0a801050686/Product/View/990700), on which you can find the ASUS A7N8X (http://www.mushkin.com/epages/Mushkin.storefront/3fb048b903d2febc273fc0a801050686/Product/View/990880#asusa7n8x).
--Stryfe
I also have read that running your RAM at the same speed as the CPU FSB promotes better performance. So this means that the PC-3200 RAM wouldn't perform as well as PC-2700?
I checked the Mushkin compatibility list and for the M/B we're talking about they dont recomend anything below PC-3200....whats the deal? They even mention that running the RAM at the CPU FSB speed is beneficial yet they dont recomend the proper RAM????? Anyone explain further??
Originally posted by Crashtec
I also have read that running your RAM at the same speed as the CPU FSB promotes better performance. So this means that the PC-3200 RAM wouldn't perform as well as PC-2700?
I checked the Mushkin compatibility list and for the M/B we're talking about they dont recomend anything below PC-3200....whats the deal? They even mention that running the RAM at the CPU FSB speed is beneficial yet they dont recomend the proper RAM????? Anyone explain further?? Err...correct me if I'm wrong, but the A7N8X Deluxe supports an FSB of 400MHz...which is the same frequency as PC3200 DDR. So therefore, you should get better performance from PC3200 RAM vs. PC2700 not only because it's running faster than PC2700, but also because it's running at the same speed as the CPU's bus.
--Stryfe
agree on muskins, good company, not the lowest prices though. they will help you out very well and find what you want.
it's easiest to buy the mb with the ram, I'd reccomend mwave.com for that, look under mb bundles in the product catalog to see what they have
also, asus is good choice
Just to give you an idea of the effect of CAS latency. Take a stick of RAM clocked at 333MHz, with a CAS latency of 2.5. Take another stick of RAM clocked at 266MHz with a CAS latency of 2. The 266MHz RAM will be faster. As long as your motherboard and RAM modules support it, of course. ;)
Originally posted by StryfeX
Err...correct me if I'm wrong, but the A7N8X Deluxe supports an FSB of 400MHz...which is the same frequency as PC3200 DDR. So therefore, you should get better performance from PC3200 RAM vs. PC2700 not only because it's running faster than PC2700, but also because it's running at the same speed as the CPU's bus.
--Stryfe
If Crashtec goes with the XP2500+, which runs at 333MHz, the fact that the mobo can run at 400MHz is irrelevant as the processor won't be transferring data that fast.;)
From the research that I had done before building my system, I understood that you would want to match the RAM speed to the CPU's clock speed not the mobo's maximum capable speed.
If I'm wrong, someone please correct me so Crashtec doesn't get anymore confused.
If the RAM can do 400MHz but the processor can't then it just means the RAM will be accessed at 333MHz instead. It also means that should you get a new processor in the future with a 400MHz FSB you won't need to upgrade your RAM to remove the bottleneck. So if you are trying to save cash, it actually works out cheaper in the long run to buy 400MHz RAM, unless you're one of those people who upgrades once every 3 years and does everything because it's all obsolete, in which case 333MHz RAM will be more cost effective. :)
Originally posted by ElfinLord
If Crashtec goes with the XP2500+, which runs at 333MHz, the fact that the mobo can run at 400MHz is irrelevant as the processor won't be transferring data that fast.;)
From the research that I had done before building my system, I understood that you would want to match the RAM speed to the CPU's clock speed not the mobo's maximum capable speed.
If I'm wrong, someone please correct me so Crashtec doesn't get anymore confused. You are correct in the fact that PC2700 would benefit him more than PC3200 at this point since he only has a 333 MHz FSB CPU.
I was talking more about Mushkin at that point. I think they are of the mentality that if you are looking at Mushkin RAM for your computer, you're going to have the best components. But it's a moot point right now.
PC-2700 is best for Crashtec with that particular CPU. (If, however, Crashtec was to upgrade to a CPU that supports a 400 MHz FSB, he might want to consider getting PC3200 RAM at that point.)
--Stryfe
So is Scikar's point that the PC-3200 RAM would be operating at 333 mhz rather than its maximum 400 mhz and therefor performing just as well as a stick of PC-2700 at its maximum of 333 mhz incorrect??
So is it less efficient performance to use a PC-3200 400mhz stick of RAM when your CPU is only capable of 333 FSB.
Maybe I should just go with the AMD XP 3200 400FSB....but its a lot more expensive and I'm not sure if it is worth the performance increase that I might not even notice very much.
I don't honestly know whether there will be an efficency issue with using PC3200 RAM at 333MHz, though I would guess that there is none. What I can say is that in the short term, using a 333MHz FSB CPU, PC2700 RAM is the most cost effective, but in the long term, assuming you will upgrade to a 400MHz FSB CPU when the price comes down, PC3200 RAM is most cost effective.
Personally, I'm planning to get an Athlon XP 2600+ CPU and I'll have Kingmax PC3200 RAM, which has an optimal CAS latency of 2.5. I'm aiming to upgrade to a 400MHz FSB processor as soon as the price of them comes down, currently when I can get a 2600+ for £70 and use the money I save to get a Radeon 9800 XT, I'm going to go with that and wait for the £200+ 400MHz FSB procs to come down in price before I upgrade the proc.
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