Explanation of Memory Specs.

[ant80]

I dont know where else to post this, so...

I was wondering what each of the specifications in a memory stand for. I understand what a SDR and a DDR is, but what is PC100,133,2100,2700 etc. And how is that different from the 333/400 etc?

Then what is CL? and what is CAS2? What do they mean by Unbuffered/Registered, and what is ECC/Non-parity?

And lastly, what is the 64x64 stand for?

I have always wondered about these. Thanks in advance.

 

[asadovsky]

Originally posted by: ant80
I dont know where else to post this, so...

I was wondering what each of the specifications in a memory stand for. I understand what a SDR and a DDR is, but what is PC100,133,2100,2700 etc. And how is that different from the 333/400 etc?

Then what is CL? and what is CAS2? What do they mean by Unbuffered/Registered, and what is ECC/Non-parity?

And lastly, what is the 64x64 stand for?

I have always wondered about these. Thanks in advance.

I'll try to answer these for you, though I'm not a hardware expert myself.

PC2100, 2700, 3200, etc. are really pretty arbitrary numbers, but they refer to the FSB speed that your RAM can operate at. PC2100 RAM can run at 266 FSB (133 before you double), PC2700 runs at 333 FSB, PC3200 runs at 400 FSB, etc. I'm not sure where the 2100/2700/3200 numbering system originated.

CL/CAS2 all refer to timings that you can set the RAM at. Essentially, the lower these values, the faster the RAM. However, there are other timings that aren't usually listed, such as "RAS precharge," "RAS to CAS delay," and others. If you want more information on this, go to www.tomshardware.com and search for "RAM timings."

I'm not sure what unbuffered/registered means, so I can't help you with that one.

ECC refers to error-checking. Most motherboards that I've come across don't support ECC (and it isn't necessary for anything). I'm not sure on "non-parity."

Lastly, I'm pretty sure the 64x64 you are referring to is just an indicator of how the RAM modules are layed out on the RAM stick. For example, you may have a 512MB stick that is 64x8.

Again, I'm no expert, so you may want to ask a few other people, or do some research. Many sites from which you can buy RAM include descriptions of these parameters as well.

 

[bjc112]

Originally posted by: asadovsky

Originally posted by: ant80
I dont know where else to post this, so...

I was wondering what each of the specifications in a memory stand for. I understand what a SDR and a DDR is, but what is PC100,133,2100,2700 etc. And how is that different from the 333/400 etc?

Then what is CL? and what is CAS2? What do they mean by Unbuffered/Registered, and what is ECC/Non-parity?

And lastly, what is the 64x64 stand for?

I have always wondered about these. Thanks in advance.

I'll try to answer these for you, though I'm not a hardware expert myself.

PC2100, 2700, 3200, etc. are really pretty arbitrary numbers, but they refer to the FSB speed that your RAM can operate at. PC2100 RAM can run at 266 FSB (133 before you double), PC2700 runs at 333 FSB, PC3200 runs at 400 FSB, etc. I'm not sure where the 2100/2700/3200 numbering system originated.

CL/CAS2 all refer to timings that you can set the RAM at. Essentially, the lower these values, the faster the RAM. However, there are other timings that aren't usually listed, such as "RAS precharge," "RAS to CAS delay," and others. If you want more information on this, go to www.tomshardware.com and search for "RAM timings."

I'm not sure what unbuffered/registered means, so I can't help you with that one.

ECC refers to error-checking. Most motherboards that I've come across don't support ECC (and it isn't necessary for anything). I'm not sure on "non-parity."

Lastly, I'm pretty sure the 64x64 you are referring to is just an indicator of how the RAM modules are layed out on the RAM stick. For example, you may have a 512MB stick that is 64x8.

Again, I'm no expert, so you may want to ask a few other people, or do some research. Many sites from which you can buy RAM include descriptions of these parameters as well.

Pretty good summary there...

 

[bjc112]

Memory Basics

This presentation can be very helpful...

 

[dmcowen674]

Bottom line, if you can get CAS 2 Memory and have your system board run stable at that level it is like Night and Day.

 

[GtPrOjEcTX]

just another FYI

PC2100 = DDR 266 Mhz
PC2700 = DDR 333 Mhz
PC3200 = DDR 400 Mhz
PC3500 = DDR 433 Mhz
PC3700 = DDR 466 Mhz

 

[NightTrain]

Originally posted by: asadovsky

PC2100, 2700, 3200, etc. are really pretty arbitrary numbers, but they refer to the FSB speed that your RAM can operate at. PC2100 RAM can run at 266 FSB (133 before you double), PC2700 runs at 333 FSB, PC3200 runs at 400 FSB, etc. I'm not sure where the 2100/2700/3200 numbering system originated.

It's the bandwidth.

 

[Jeff7181]

Originally posted by: dmcowen674
Bottom line, if you can get CAS 2 Memory and have your system board run stable at that level it is like Night and Day.

I dunno about night and day... noticeable in benchmarks... but rarely do you ever really "feel" the effects of RAM timings. I'm using my 2nd rig right now, and the memory timing is at 5-2-2-2... I use to have a different stick that I had to run at 6-3-3-2.5 and I can't say I notice a difference at all.

 

[ant80]

Wow!!! That presentation was pretty helpful. I wish I had such a presentation for all my classes. But thats just wistful thinking.

 

[KillaBong]

Like he said the pcxxxx is the bandwidth. pc2100 = 2100mb/s or pc4000 = 4000mb/s.