FPU overclocking

[A6000]

Hi, just recieved my "new" 4000d today, I have never seen so much dust as I saw when I opened it up, I am thinking of giving it a thorough cleaning before I start to use it, I can already see that I will have to replace the battery.

The machine is fitted with an a3630 cpu board which apparently has sockets for an FPU, I have read that little software requires an FPU but I have one so I may as well fit it.

I have a 16mhz xc68881 pga, can this work at 25mhz without shortening it's lifespan or can it run at 16mhz without "tripping up" the 68030.

Thanks.

P.S anyone tried overclocking the motherboard, any model?.

[Argus]

iirc the a3620 board uses a PLCC type fpu socket.  The 68881 may be overclockable to 25MHz but you'd be better off just finding any old 68882 and putting a 50Mhz crystal directly on the cpu card and enabling the jumper for the separate fpu clock.  Most if not all 68882s should operate at up to 50MHz w/o problem (I have a 40MHz 68882 overclocked to 50MHz on an old A2620 card in my A2000 and it works great).  The fpu will speed up certain math-intensive operations that utilize the fpu libraries.  Better yet, just find an old A3640 card with a full 68040 chip and you'll have a much faster fpu than any 68881/2 ever made (though the tradeoff is you'll find motherboard RAM access speeds are slower with the 68040 than the 68030 you already have).

It is possible to overclock the motherboard but you're asking for trouble as you'll lose Zorro slots or other timing problems will pop up.  I never did it myself but ask redrumloa about it; he was able to speed up the AGA display by overclocking the motherboard, iirc.