• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

of 2100, 2400, and overclocking

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.

Chris-the dude

Feb 10, 2002
Chicago burbs
Hello Overclockers,

I've been reading through the forums for a few weeks now, and I've still got some questions about DDR memory that are bothering me.

Ok, I understand how to calculate theoretical bandwidth. Please correct me if I speak incorrectly about something.

FSB * 2(double data rate) * 8(bytes per cycle) = Bandwidth(MB/s)

example: 133Hz *2*8 = 2128 =approx= 2100 MB/s

Now, I start to get confused when it comes to 2400 and 2700 bandwidths. for these to operate at advertised levels, the FSB would have to be 150 and 166 respectively. I also understand RAM is backwards compatible, so if you plugged a 2700 chip into a motherboard with a 133 FSB, it would operate at 2100 MB/s. So, to achieve 2700, you would have to raise FSB to 166. So someone would only want to buy a 2400 or 2700 stick if they were planning on overclocking or already had a higher FSB.

However, I've heard that on many motherboards you can change the memory clock speed without changing FSB by raising it manually and lowering it through dividers. Is this right?

So if I had a 133 FSB machine that I knew I wasn't going to try to go much past 150 FSB, wouldn't I be safe buying a cheaper stick of 2400 ram like this instead of the more expensive crucial ram?

I look forward to your comments

Chris-the dude:burn:
Yes, some mobo have an option that allow you to change the ratio of mem/cpu, for example, a ratio of 4/3 means that if your cpu is running at 133FSB, then your memory is running at 166, which is DDR333(pc2700). With the new Kt333 chipset out, DDR333 is finally supported on mobo, so you don't need to overclock your cpu, and you memory is still running at DDR333.

If you are buying a new mobo soon, then you better get the pc2700, since new mobos support the new standard already, and your system will have a better performance. Even if you are planning to buy an older mobo, its still a safe move to buy pc2700, since you dunno when you will be upgrading to another mobo which support the newer chipset.

but if you are on low budget, and not going to OC past 150FSB, then the pc2400 would be enough for you. its your call.:D
Thanks, just what I was hoping to hear.
Well, except the b*tch and the ni**a.

I think I'm starting to understand this memeory junk pretty well now.

Chris- the dude