CPU Clock Multiplier

[6583]

I have a Soyo 6BA+IV motherboard. I saw the Anandtech review for this motherboard. It shown that the multiplier is from 2.0x up to 9.0x, but my motherboard has only max of 8.0. Anyone knows about this?

6583

 

[Peter]

Nevermind, the Intel CPUs which can be bought by ordinary people (production run stuff, not engineering samples) ignore the mainboard's multiplier setting anyway. They always run at their internally fixed ratio.

Regards, Peter

 

[6583]

Oh ok, btw, are you using this motherboard also? Thanks

6583

 

[sleepdragon]

updating the bios should help

 

[compuwiz1]

The multiplier displayed in the bios is inconsequencial, as it will read from the cpu and default to that. I believe the chipset can do this internally up to 12x. It wont matter if you set it to 3x, it will still default to what the cpu is locked at. Just set your fsb where you are going to run it and enjoy.

 

[Peter]

compuwiz,

don't confuse people with complicated (and wrong) explanations.

Again, here's how it works:

The multiplier you set on the mainboard (by jumpers, switches or BIOS) is just a setting fed into the CPU on reset. In case of socket-370 or slot-1, this is a four-bit binary number.

The CPU reads this value on reset, and then sets its integrated clock multiplier circuitry to whatever it was designed to do with this setting. Intel processors ignore the provided setting altogether, they are factory preset to use a constant multiplier.

Only engineering sample Intel CPUs actually read the multiplier setting from the mainboard. Newer ones remap the old low settings to multipliers 8.5x and higher, but still use the same four pins. Jumper/switch type mainboards can provide any multiplier, and in jumperless boards, you might have to set a low multiplier to get one of the new high ones (like setting 4.5x to actually get 8.5x). Again, this is needed for engineering sample CPUs only.

The mainboard, let alone the chipset, isn't involved in the generation of the CPU internal clock AT ALL. This high clock exists only inside the CPU. Ain't no such thing as external or internal multiplication - it's been internal to the CPU ever since the 486DX2 first used a higher core than bus clock.

What this means is if you walk into a shop and buy an Intel CPU today, don't care about what multiplier it "requires" and what your mainboard can be set to. Your new CPU will ignore whatever you set there anyway.

Regards, Peter

 

[Frenchie]

I have the +IV and the max multiplier that the board would show was 8.0x; It would run 8.5x without a problem, it just wouldnt show the proper multiplier or fsb. If you flash the mobo to the 2ba2 bios, the mobo will be able to properly display multipliers above 8.0x.