DaveW wrote:
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.

--
Nate Edel http://www.cubiclehermit.com/

"What's the use of yearning for Elysian Fields when you know you can't get
'em, and would only let 'em out on building leases if you had 'em?" (WSG)