Probably a stupid question about FSB

[sswingle]

Ok, I had assumed that my FSB ran at 266 MHZ, and newer motherboards run at 333 or 400.

Why then, do people run their FSB at 200 when they are overclocking?? For example, putting the fsb at 200 to overclock a 2500 to a 3200.

Isn't 200 really slow?? Is it just that FSB doesn't matter that much, or am I completely wrong about something.

 

[Sid59]

266 = 133 x 2
333 = 166 x 2
400 = 200 x 2
-------------------
effective = real x 2

you are refering to the effective FSB and people who are overclocking are refering to the real FSB

that's for AMD Chips

Intel is x4
400 = 100 x 4
533 = 133 x 4
800 = 200 x 4

 

[paco83]

AMD motherboards have a 2x multiplier. So when people run their "true" fsb (fsb used to calculate processor speed fsb*mult) at 200, they are actually at 400. Your 266 is actually running at 133, 333 at 166 ect.

 

[sswingle]

Ah. I understand now 🙂 Thanks!

 

[InlineFive]

Likewise the Pentium4s use a Quad-Pumped FSB.

 

[joe2004]

FSB is the interface between memory and CPU, nothing else. The DDR memory runs are having double bursts in one cycle therefore while the FSB has 133 MHz cycles the memory actually has effective frequency of data output of 266 MHz though the cycle frequency is still 133 MHz. That is the source of all the confusion. With old SDRAM the effective frequency of data bursts and the frequency of cycles was the same.