Would a 533 Mhz FSB processor work in a 400 Mhz motherboard?

Hi all!

Will it scale down to 400 Mhz, or won't it work at all?

I am asking because the fastest CPU that my machine can
take is P4 2.6 Ghz, 400 Mhz FSB. But I am having trouble
finding 400 Mhz FSB cpus, whilst there are plenty of
533 Mhz FSB cpus on ebay.

There are even Xeon 2.2 Ghz, which run at 400 Mhz FSB,
but somehow I don't think my old Dell Dimension 2350
can run a Xeon! It came with a 2.2 Ghz Celeron.

Thanks in advance!

Buck

 

Hey, I think I found the answer to my question!

http://forumz.tomshardware.com/hardware/533mhz-FSB-P4-ftopict58486.html

And the OP even has the same board chipset as me, so we're in
the exact same boat!

 

* Buck Rogers:

So what? Just having the same chipset means zero. The point is if the
BIOS of your Dell will accept the unsupported CPU, and even if it runs
it probably lacks the proper microcode for it...

Benjamin

 

No you CANNOT use a 533 MHz bus CPU in a 400 MHz bus board. (RAM sticks can
run at lower speeds safely, but CPU's cannot.)

 

That depends on how you mean "cannot run at lower speeds."

I've underclocked CPUs just fine, many times, without any problem, including
- purely to see how it would run, my new Pentium D - which runs quite
happily at 2128mhz rather than 3200. That said, with modern CPUs (P4s,
Athlons) that has been via board settings on boards that support a given
CPU, *not* via plugging a CPU into an older board that didn't support the
speed.

And back in the Slot 1/Socket 370 days, it was often (depending on the
individual chipset/motherboard combination) safe to run a 133mhz or 100mhz
FSB chip in a board that only supported 100mhz or 66mhz (don't recall ever
seeing a 133mhz chip tried in a 66mhz board, though!)

I knew a guy who ran a 133mhz chop (a P3/800, IIRC) at 100mhz most of the
time, since the BX chipset wasn't officially spec'd to run at 133mhz.
He'd normally run it underclocked, and then reboot and switch it up for
playing games.