Trying another motherboard with a standard form factor might prove more
difficult to install than one might think in the computer case you describe.

With the HP you might want to look at the MB chipset first.  They have a
northbridge and southbridge but the northbridge is the more important one as you
do not mention changing your hard drive.  Makers of chipsets include
manufactures like VIA, SIS, or Intel.  If you do a search of www.oempcworld.com site
they tell the maximum bus speed of most chipsets.

The 2.0X multiplier for AMD becomes 6.0 x so even a 66 MHz system will run at
396 MHz which is close enough to 400 the CPU won't mind.  Your board also
need to have the CPU core voltage setting of 2.2V or lower.  There are some AMD
that can take 2.4V but they are scarce.  Finally, while not as fast the Cyrix
CPU can take much higher core voltages and would offer a lot of improvement
over a 166 pentium.

Your motherboard board should have jumpers indication the possible voltages
of CPU core and bus; the bus speed in MHz i.e. 66, 83, 95, 100 and the
multiplier which gives the CPU speed.  They are usually defined somewhere on the board
as small decals near the various jumpers.

I have increased some early socket 7 Intel chipset motherboards from 400Mhz
to 600 MHz using the AMD K-6/2 or AMD K-6/3 CPU's.  Your will also like need
more RAM.

Good luck,
Mike Scott

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