RAM question

[hamlet]

I would consider myself intermidiate in computers, I have helped build a few and know the basic tasks each component performs, but I want to learn more. So here is my question on RAM, what do the numbers mean to me? I know that a 8G of RAM gives you more space than 4G. But what are the values behing the description DDR3 telling me. (DDR3 1600 (pc3 12800)) I have noticed 12800 seems to be associated with 1600.

Timing, what is the difference between 9-9-9; 9-9-9-24; and 9-9-9-24-2N?

Cas Latency, what is this?

Finally, how much of a difference will i see with these numbers changing? I do a lot of gaming and even more CAD so performance means a lot.

Thanks guys.

 

[PP Mguire]

Those are the RAM timings. The higher they are the looser they are, the lower the tighter. Lower numbers mean better performance like higher MHz (speed) means faster performance. The higher the MHz, the lower the timings, the better the RAM generally speaking. That isn't always the case though. RAM voltage on Intel rigs (Core i specifically) is limited to 1.65V of you are taking a risk at damaging the IMC (Memory controller) which is built into the CPU. This being said, lowering timings on a kit already set to 1.65v could become unstable which would result in lower performance due to compensation, or just a simple crash.

Truth be told, anything past 1600MHz 9-9-9-24 is minimal gains and wont really be seen in real world performance due to memory bandwidth being so high compared to todays tasks. Just what happens when computers start getting so fast.

The difference between the 3 you named off is simply an extension to the set of timings. In other words, they all mean the same just one is showing another number in the set. 2N is also called 2T. Back in DDR days you wanted that number to be 1 as it is your main cas latency. Typically DDR3 kits are 2 which is normal. Faster kits in the 2133+ area are usually 3T but can mostly be run at 2T even at those speeds.

If you want a more thorough explanation check this link out.
http://www.hardwaresecrets.com/article/Understanding-RAM-Timings/26

 

[hamlet]

thank you PP.

Can you explain to me what cas latency is?

 

[PP Mguire]

I could copy and paste the exact description, but basically it is the delay in the communication between the controller and the stick and the stick to the chips.

 

[hamlet]

ok, thankyou!

 

[PP Mguire]

No problem. I'll say in short, long as you are 1600 9's you are good and wont really see much for performance until memory controllers get a boost from DDR4. That wont be for a few years yet, so not much to worry about.

 

[Veraster]

I happened to click on this thread and when I did so, I realized I'm an idiot. One time I bought ram with a CAS latency of 11 thinking that the higher number meant better performance because I didn't bother to do any research. What difference does that make in real world performance vs ram with a CAS latency of 9 anyway?

 

[PP Mguire]

Not a whole lot. You wont notice the difference when gaming or running Photoshop or anything.