RAM Question

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maddrummer

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Ok, sorry for the ignorance.....

So there is RDRAM, DDR RAM, and SDR RAM....right? So whats the better one? Also, when it says something like PC1033, what is that in reference to?

Thanks
 
There are two types of SD RAM.

Standard SD RAM is the "old" type.

DDR SDRAM is the "newer" type.

DDR SDRAM is faster because it travels at twice the speed as SDRAM. Actually... I should say, it travels as the same speed, it just does twice as much at the same time. DDR stands for Double Data Rate, which means that it can process data going "in" and "out" at the same time. The older SDRAM can only process one "direction" at a time. (that's putting it in pretty general terms, but you get the idea)

RD RAM is (kind of) a totally different type of RAM used for P4's. (Also known as RAMBUS RAM).

The type of RAM you use will determine what kind of motherboard you have to get (or vice versa). There are some motherboards that support both SDRAM and DDR SDRAM, but you can't use them both at the same time.

The PC2100 (etc.) stands for the data transfer rate (2100 = 2.1 GB/sec) The "PC" type that you get must correspond with the FSB (front side bus) of your CPU and mobo. So if you get a DDR 266 motherboard, and then go out and buy PC2700 RAM, you're wasting your money because the data rate of the mobo can't handle more than PC2100 RAM. This naming convention applies to the two types of SDRAM. When you get into RDRAM, it's not so cut and dry... (i.e. PC1066 actually has a 2.1 GB bandwidth)


It is kind of confusing and you just have to get used to what goes with what and all that crap, but once you get to know the general idea of what to look for, it's not so bad.

As for what's "better". Well... for an Athlon, the DDR is better... and the DDR 333 is generally regarded as the best way to go right now (since DDR 400 actually gets outperformed by DDR 333 in some cases and hasn't really justified its own existence yet)

When it comes to P4's, well... most people just go with RDRAM, but some still prefer to use DDR RAM with P4's. I think that battle is still up in the air, but I'm not too sure since I don't deal with Intel stuff much.


WATYF
 
I could be mistaken, but I think you meant PC133, not 1033. This refers to the speed of the RAM. (If it is actually 1033, then that would probably refer to the bandwidth.)

you need to get RAM that is compatible with your motherboard. check your manual for what kind it expects.

Beyond just the type of RAM, the important points are its capacity and its speed. When someone says they have 256MB of RAM, they're talking about capacity. They can have 256MB stored in RAM at one time. The "133" in PC133 refers a speed of 133Mhz. The speed contributes to the bandwidth of the RAM, which is key to its performance.

Let's look at DDR as an example. DDR uses 64 parallel bits that it can switch. There are 8 bytes in a bit, so the chip can switch 8 bytes at once. DDR, unlike other types of RAM, switches two times per cycle. So: 2 * 133mhz * 8 bytes = about 2,100 MB/s. This is what people call "DDR 2100 RAM". DDR that runs at 166mhz is called DDR 2700.

This speed is also limited by your motherboard. If your board (or your processor) can only run at 133mhz (and it can use ddr), you can use DDR 2700, but it will only be able to run at 133mhz, and it will behave like DDR 2100.

So in the end, you should try to get the fastest RAM that your motherboard can handle. Having lots of PC100 RAM won't make up for the fact that it's only running at 100mhz.

Hope that didn't confuse you more.
 
one minute too late ... now i'm just repeating what you already know :)
 
WATYF said:
When it comes to P4's, well... most people just go with RDRAM, but some still prefer to use DDR RAM with P4's. I think that battle is still up in the air, but I'm not too sure since I don't deal with Intel stuff much.


WATYF
Click to expand...

Not true. Of the two chipsets available for P4's, the i845 is far more popular than the i850.

The i850 was the original P4 motherboard chipset that supported RDRAM. Intel introduced the i845 chipset to support DDR RAM because they finally realized that DDR was much cheaper than RDRAM with no major loss in terms of performance.
 
Cool I totally understand now, Just all the numbers jumbled together got me confused. Yea I'm upgrading my system and I'm seeing what works with what between motherboards and RAM and all. The chipset thing had me confused to but I think I get it.

Thanks so much
 
brzilian said:
Not true. Of the two chipsets available for P4's, the i845 is far more popular than the i850.
Click to expand...
yeah... thus the "but I'm not too sure since I don't deal with Intel stuff much."

RAMBUS was a dog when it first came out, and DDR came in as the low cost solution, but I'm just not familiar enough with the RAMBUS vs. DDR thing to know which one is a performance leader/popular choice at the moment. I may have to research that soon, though, since I'm actually considering (*shudder*) going to a P4 on my next system. :p The XP 2800+ just doesn't hold up as well to the 3GHz as I'd like it to... but on the other hand... it costs half as much, so who knows. Maybe I'll still stick with AMD... one thing's for sure... I'm not waiting for the Claw Hammer to come out... sheesh... I'd like to buy my new system sometime this decade. :p


WATYF
 
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