Motherboard upgrade / memory advice

[sonic_scott]

Hi everyone

I have to change over my mother board and need a lil help if you can

the socket is 478 , I basically know how to change over the motherboard , I just wanted to know what would be the best one to use for PC3200 memory ? , i read someplace that PC3200 is the same as DDR400 is that true ? . I was in my local computer store looking over motherboards (for pentuim 4 by the way ) and i paniced and didnt buy anything because of the DDR thing , most of the motherboards use DDR 400 that i saw.

the reason i am trying to find a motherboard that takes PC3200 is because i have a GIG memory in this computer i have just now and would rather use what i have than buy new memory and have the others useless (i could sell them on ebay but i dont need more grief in my life lol).

So , i just wanted to see if any of youÂÂ! could maybe give me adviceÂÂ! ÂÂ! , thanks for your time
oh , the computer i have is an Advent T1000 by the way ÂÂ!

[syphus]

Hi Sonic_Scott, welcome to itsallPC

DDR has two naming standards, which can be rather confusing.

As many will recall, prior to DDR, single pumped RAM (what we now call SDR) was named PCxxx, where xxx was the clock frequency. PC100 for example, ran at 100 MHz. DDR is a double pumped bus which means that for ever clock it transfers a two bits, one on the rising edge of the clock and one on the falling. This effectively doubles the data throughput, hence the name; Double Data Rate.

In order to immediate distinguish the difference between SDR and DDR (note that some people make the mistake of calling SDR SD-RAM, but DDR is also a type of SD-RAM), they decided to prefix the speeds with DDR. Of course, it could still be confusing to people if they used the real clock rate, after all, that fact that DDR100 would be about 30% faster than PC133 would be difficult for people to understand, so they opted to use the data speed.


DRAM Clock
66 MHz
100 MHz
133 MHz
166 MHz
200 MHz

SDR
PC66
PC100
PC133
Never used
Never used

DDR
Never used
DDR200
DDR266
DDR333
DDR400


In an extreme marketing oriented move, it was also decided that the frequency needed to be downplayed in favour of a much bigger number; the bandwidth. The most confusing part is the decision to use the suffix PC for the bandwidth, where the suffix was previously used for the clock frequency. I suppose this was done for the sake of familiarity, or perhaps to make DDR look so much better than SDR. Who knows. Anyway, bandwidth can be calculated very roughly, like so:

(DRAM Clock Frequency * Pumps Per Clock) * Interface Width bits / Bits per byte = Bytes per second

The Pumps for DDR is 2, the interface width for all SD-RAM is 64-bit, and there are 8 bits per byte. For DDR400, the calculation would be:

(200 MHz * 2) * 64-bit / 8 = 3200 MB/s

Hence, PC3200. Note that because we put in Megahertz, we get Megabytes out. This is the full table for certified DDR SD-RAM.


DDR
DDR200
DDR266
DDR333
DDR400

Bandwidth
1600 MB/s
2128 MB/s
2664 MB/s
3200 MB/s

PC
PC1600
PC2100
PC2600
PC3200



The fastest certified DDR solution is Double Channel DDR400. Double channel is a method of doubling the interface width; rather than 64-bit it is 128-bit.

(200 MHz * 2) * 128-bit / 8 = 6400 MB/s

As you can see, this theoretically doubles the bandwidth. It is well worth upgrading to Double Channel if you have a Pentium 4 processor with a FSB of 533 MHz or higher.


I hope this sufficiently answers your question.

[sonic_scott]

thanks alot syphus for the info - very much appreciated ÂÂ!

whoops - i also should have added - thank you for the warm welcome hugzzzzzzzzzzzzzzzzzzz