FSB MHz and RAM MHz 2

[8humhum8]

so anybody know why they sell 800MHz ram for 400MHz front side busses (which just came out anyway?)

 

[gwinn7n]

400Mhz FSBs are not new in computer time. Its been around for a little while.

800Mhz RAM is good for the CPU chips and motherboards that support them, namely the newer P4s. Plus, you have components on your motherboard that speak directly to the RAM outside of the CPU.

So, if a person bought 800Mhz RAM and put it in a system that only supported 400Mhz FSB, it was obviously not a good purchase decision, unless there are other factors we are not seeing.

Gary
gwinn7
A+,N+,I+

 

[cdogg]

800MHz frontside buses (FSB) is a little elusive. Actually, we're talking about a 100MHz FSB, which has been "quad-pumped" (four times as much data per clock cycle). They advertise it as a 400MHz frontside bus, when in reality it's a 1-lane highway expanded to 4 with the same speed limit.

Still confused? It gets better!

Now they have DDR memory that can run together - Dual DDR SDRAM. So, when you pair two DDR-400MHz modules together, it's like widening that highway to 8 lanes with the same speed limit. Theoretically, you have the thoroughput equal to an 800MHz FSB, but it's only running at 100MHz (multiplied by a factor of 8). You can accomodate more traffic this way, but simple requests will still travel the same speed. In other words, your office applications or internet browser won't notice the difference.




~cdogg

"The secret to creativity is knowing how to hide your sources."
- A. Einstein

 

[dakota81]

I believe he's talking about RDRAM at 800MHz, not DDR RAM? I've never dealt with RDRAM so I don't know how the specifics of it works, but I know the PC800 RDRAM is designed to work with a 100MHz clock (which are the marketted 400MHz FSB P4's).

Maybe search for a page that describes RDRAM technology or someone else here can describe it in more detail?

 

[8humhum8]

thanx people. i get the idea.