fsb speed

[skullman80]

thinking the problem i may be having installing windows is related to fsb.

I have the fsb set to 266mhz on the motherboard. first set to 333 then down to 266. When i go in the bios it is only showing the fsb speed as 133mhz?


link to motherboard

http://www.xfxforce.com/mb/product_...hp?sku=KT400ANB

anyone know why that is?

or how to change it?


i am using a pny stick of pc2700 ddram 333mhz.
athlon xp 2000+
20 gig hard drive
geforce 440
burner

hdd set as primary master
burner as secondary master...

any ideas??

thanks
alan

 

[franklin97355]

FSB can be set to 100 or 133 plus a multiplier.

 

[dakota81]

You can thank the cpu maker's marketting teams for this confusion. Digital circuits are almost always driven by a clock, and they have their registers & flip-flops & other logic trigger on either the rising edge of a clock pulse or the falling edge of the pulse but not both.

Now enter DDR, which triggers on both the rising & falling edges, thus to the circuitry, the clock appears to be twice as fast as previously.

133MHz clock appearing to be 266MHz; thus to marketting teams, 266 is a better selling number than 133, and we have our confusion... =Þ

A 266MHz FSB runs on a 133MHz clock for the Athlon.
A 333MHz FSB runs on a 166MHz clock.

The correct setting for your cpu is a 133MHz clock.

 

[cdogg]

dakota is right on, but I wanted to add a few things...


Although an advertised 266MHz frontside bus is running at 133MHz sending twice as much data, it is important to understand that it is not twice as fast.

Think of it this way. If you had a highway that was widened from 2 lanes to 4, but the speed limit stays the same, does that help you get to your destination any quicker at say 2:00 AM in the morning? No. When traffic is low, you could care less if you had a 2-lane or 4-lane highway.

Dual-pumped buses relate in the same way. Yes, data is being sent on the rising and falling end of each cycle, but if the extra bandwidth is not needed (as in many office applications), you're not going to notice a difference. A frontside bus running at a true 266MHz would be more efficient. However, due to limitations on the length the FSB path can be, it is harder to raise the speed and still operate efficiently (which is why you don't see true 266MHz FSB's).

Don't get me wrong! Dual-pumped is better than nothing!! Just had to get that out...

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