Confusion about two not identical 3630 boards.Advice needed !!!

[Effy]

I am the almost happy owner of 3 A4000´s, although none of them is operational. But that´s only a minor detail  :-D
I am preparing one of them to sell and spend the money on the other two such as an accelerator or so ...
The problem now. Two of the A4000´s have got a 3630, the third one has got a 3640 that is gonna get an Xcalibur in the next coming days (I hope so). Now about those 3630. I thought they were all almost similar according to the Big Book ...
But they are a bit different. Both have got an 68EC030 processor, but then the difference starts. One has got an fpu the other one doesn´t. The one without fpu has got no occilator next to the processor and the one with fpu has got a 50 Mhz occilator next to the processor. Does this mean it runs on 50 Mhz like the Blizzard 1230/4 or is this like a 68040 board where 50 Mhz means that the processor actually runs on 25 Mhz

[Ilwrath]

The oscillator only controls the FPU clock, and I believe it's a straight-through clock.  (in other words, your card should have a 50mhz FPU onboard.)    The 68EC030 is still clocked from the mainboard at 25mhz, and would be, regardless of what (if any) FPU oscillator is seated on the 3630 card.

[stefcep]

Hang on.  this is wierd..I think what you have is one A4000 which has an 68030 cpu card in it (the A3630) and the other A4000 has an 68040 cpu card in it (the A3640).  The A3640 had a 68040 running at 25 mhz which had a built in fpu.

[Lemmink]

The FPU was optional for the A3630 and the oscillator supplies the FPU clock if the clocking of FPU is set so asyncronus by the jumpers. Most of the A3630 only have a socket for PLCC FPU that only go up to 40 MHz and only the holes for a PGA-Socket. A few actually had the PGA FPU Socket soldered in allready. Maybe only the early ones and it was skipped in later productions runs to cut cost, as those who wanted mor power usually got an A3640 insted of upgradeing the A3630.

[Effy]

The fpu is actually plugged on the board, the fpu is a processor with a lot of pins at the bottom ...
Is this a good thing Does this mean the fpu runs at 50Mhz Has this got any use if the main processor runs at only 25 Mhz