FSB vs. Multiplier

Mitch?

Mitch?

banned
Okay. I've got a few questions. Now i know what fsb is, or whatever equivalents the respective chipmakers have, but how do multipliers affect stuff? I'm assuming a 3.2ghz overclock would be more beneficial with a 400fsb*8 multi, rather than 200fsb*16? taking into account memory speeds and such also.

Anyway - how the hell does a multiplier factor into things?
 
The multiplier is the factor that determines the CPU speed, as you said it is multiplied by the FSB to determine the clock speed. Multipliers are upwards locked on all processors except for BE/EE versions, so they can only be lowered (usually only by 2x), that can be used to achieve the same CPU speed but with a faster FSB.

Most Core 2 Duo's/Quad's have a 266MHz FSB which gives an effective bus speed of 1066MHz. (Not really relevant, but just giving you all the info).

266 x 8 = 2.13GHz
266 x 9 = 2.40GHz
266 x 10 = 2.66GHz

etc, etc. That's how Intel determines the speed of their processors, for instance the Q6600 and Q6700 are exactly the same, except the Q6700 has a multiplier one higher then the Q6600.
 
With a AMD using Hypertransport, raising the bus higher with a lower X doesnt really improve performance any. Your not using all the HT bandwidth anyway. So having a unlocked X helps, all you really need to raise is the CPU voltage. The Bus and memory stay at stock speeds.

Running a Intel before the i7 having a higher FSB improved performance because it raised the bandwith between CPU and Northbridge/Memory and it needed it.
 
thanks guys. because i did the same (or a few mhz off) oc on my 5400, and they super pi'd like the same. i thought you'd ge tmore outta fsb, but, **** me huh.
 
I did a test where I had my Q6600 at the same clock speed, but one with a lower multiplier so I had a bus speed of 2,000MHz. I ran SuperPi and got a difference of like 0.5s.
 
Yeah with a AMD you wont see any performance difference. But using your bus does overclock your memory unless you bumb the speed back. So you might see alittle performance if your using the bus to overclock your memory.
 
So, there isn't a difference with me using a X8 Multi and a higher FSB over the stock X9 Multi?

Wouldn't I require more vCore with the X8 as the FSB would be higher?
 
Yeah with a core 2 still using a higher FSB, there might be a slight performance gain. The voltage to the processor itself should not take more at the same ghz. But with a really higher FSB the Northbridge might need alittle more voltage.
 
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