Upgrading CPU & Cache on Miata

[Stefan van der Eijk <s vandereijk chello nl>]

Hello,

I've got a Miata at home, originally a 433au. I've purchased 2Mb
external
cache for the machine, which works fine. Recently I've upgraded my CPU
to 500MHz (swapped it with a friends 500a). I've now noticed that the
external cache isn't working when The machine is running at 500MHz. 

Is this normal? Are there different cache modules for 433, 500 and
600MHz?

Here's a little test I did yesterday (rpm --rebuild licq):

433:
816.52user 45.36system 14:56.15elapsed 96%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (485269major+481903minor)pagefaults 0swaps  

433+2Mb:
579.50user 36.52system 10:51.80elapsed 94%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (485421major+482352minor)pagefaults 0swaps  

500:
764.08user 44.14system 14:03.28elapsed 95%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (488282major+484036minor)pagefaults 0swaps  

500+2Mb (but not seen in bios):
768.98user 43.85system 14:05.67elapsed 96%CPU (0avgtext+0avgdata
0maxresident)k
0inputs+0outputs (485210major+481884minor)pagefaults 0swaps

Can anyone shed some light on why the external cache doesn't work at
500MHz?

Thanks!!

Stefan van der Eijk