Overclockinga ZipGSX, advice please

["macdog" <bigdog128@gmail.com>]

I am trying to overclock a ZipGSX I just picked up.  I have it running
at 10 Mhz, rock solid.  When I got it, it had no oscillator or cable,
and it had an 8 Mhz WD 65816 PLCC chip which I replaced with a 14 Mhz
version.  I successfully used 7, 8, and 10 Mhz (27, 32, 40 Mhz)
oscillators so far.  So far, when I have attempted to install faster
oscillators, the GS has not booted.  Not even a checkerboard
screen....It just acts dead.  I note that the ram cache has chips that
end with a 7.  I assume them to be 70 ns.  In order to bump up the
speed even more, I think I heard that I need to speed up the Cache ram
to something faster.  Does anyone have any experience doing this kind
of thing?  I would appreciate any advice on this endeavor.  Thanks.
Macdog, aka Jamie Steffens.