FSB compatability question

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Trotter

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Something I have wondered about, but have not found an answer to...

If a mobo can only handle up to a certain rate of FSB, could you use a CPU that has a higher FSB?

For example, the BIOSTAR U8668 D is rated for 533/400MHz FSB. Would a P4 2.8E 800MHz FSB CPU work in that mobo? Would the CPU be restrained to the max FSB that the mobo can go with, or would the setup just not work?

I ask about this as my mobo is rather old, and can only handle up to a 266MHz FSB. I can find Athlon XP CPUs, but mainly of higher FSB than that.

Anyone actually have a solid answer? i don't need a "Pop it in and see if it does" type of reply. Preferably an answer with links to documentation... but I guess I can't have everything.
 
Assuming your board is a Socket A it will operate with any Socket A chip regardless of FSB speed considering that is really only a BIOS setting and a motherboard can handle many different FSB speeds with a little bit of tweaking

Flashing BIOS to lastest version would assure this as much as possible and you might have to manually adjust the FSB in your BIOS and possibly bump up the chipset voltage so it can handle it but the FSB is variable so the motherboard really isn't the limiting factor

In this case you have PC2100 which will really slow down a 333FSB core right now
 
OK. Cool.

Well, the mobo only handles up to PC2100, unfortunately. Like I said, it is old.

The Compatability Report for it shows up to the 2600+, but that may have been all that was available at the time it was compiled.

Thanks, mi amigo.
 
Supporting memory speed isn't an issue here...FSB speed and memory bus speed are synchronized meaning if you have a 333MHz FSB chip you can shove in DDR333 and they will work together

Any DDR will work in any 184pin DDR DIMM slot regardless of what the board specifies so long as it supports single or multi sided modules and you have the ability to bump the FSB speed up that high...the only issue might be with chipset issues or vdimm but I doubt it

Your motherboard simply says PC2100 as that was the current AMD FSB standard at the time...same thing with A64 boards supporting DDR400 because of a 200HTT yet you can pop in DDR600 by all means and it'll work

BIOS is flexible and that's what dictates your operating frequencies, assuming you have the ability to change things, namely the FSB, you should be able to add any socket A chip or any DDR1 module...the only thing that might pose an issue would be PCI/AGP frequency locking
 
Trotter....
I'm inserting two links that may answer your question.
http://en.wikipedia.org/wiki/Front_side_bus

The second link basically states: "the Cpu and chipset go hand in hand for optimum system operation, because manufactuteres optimize chipsets to work with specific Cpus".
* You can put the fastest CPu in that fits your mobo, but the system speed will be limited by your other sys. components; namely chipset, Ram, Agp,and PCI .
http://computer.howstuffworks.com/motherboard3.htm
 
It should work, you'll just need to basically overclock the FSB to what the cpu's fsb is. To the mobo, it's O/Cing. To the cpu, it's not.
 
Well, the comp is a pre-built, so overclocking it ain't an option.

If I get another socket A, it'll just have to run a little slower.
 
That is in the future as well.

She's already told me that this one becomes hers when I build mine.
 
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