A3000/16mhz to 25mhz

[desantii]

Can a 16mhz Amiga 3000 be converted to a 25mhz model? There are several jumpers to change and of course the crystal would have to change but has anyone done this? i am sure the 030 can take teh 25mhz but the 68881?
 
thanks

[Darrin]

This doesn't really answer your question, but if you ever see one of the stock Commodore 68040 25MHz cards that came with certain A4000 models going cheap then grab one as they work perfectly in the A3k (you may need to change the CPU cooling though).  I put one in my A3K when I upgraded my A4K.

[Pentad]

Can a 16mhz Amiga 3000 be converted to a 25mhz model? There are several jumpers to change and of course the crystal would have to change but has anyone done this? i am sure the 030 can take teh 25mhz but the 68881?
 
thanks

Back in the day, I had an Amiga 3000 25 MHz and my friend had an Amiga 3000 16 MHz.  He easily over clocked it to 25 MHz without problems.

The only down side is that the Amiga 3000 16 MHz has the 68881 and not the 68882.  The 68882 is twice as fast as the 68881 at the same speed.

However, it is a very cheap way of go to 25 MHz!


-P

[Zac67]

According to Motorola, the '882 is 40% faster with some instructions, in reality it's more like 10-20%. According to comp.sys.m68k it's 240 vs 264 KFLOPS @ 25 Mhz (gosh!). Due to better pipelining, the '882 topped out at 50 MHz though ('881 25 MHz). Yours may run at 25 MHz or maybe not but chances are good.

[VingtTrois]

One of my A3000@25MHz has a hack to have the FPU at 50MHz without any problems.

[touringsedan]

It would seem that with a new oscillator and moving your jumpers to the 25mhz settings would work, but my 68030/16 reached the temperature of the sun.
A heat sink wouldn't help this poor little CPU.
Like with all CPU's you can't be certain how it will react to increasing the clock speed, just try it and watch the temps.

But honestly, its much easier to find a fast slot CPU card then to risk damaging your existing motherboard.

My A3000D/16 has a 3640 Rev 3.1 working great in it, just had to improvise a better heat sink solution.

[desantii]

I will try this over the weekend to see if it runs at 25mhz.. if not I'll look for an 030 card as I really want an 030 for compatibility reasons
 
thnaks

[touringsedan]

Hmm.. Well if compatibility is key and if your CPU can't handle 25Mhz, it maybe possible to use a A3630 while keeping the 50Mhz crystal on your motherboard, as this card uses the timing from the motherboard.

On second thought, this still may over clock your onboard 030 and burn it up.

I don't have a 3000 with a socket for the oscillator or I would try it for you.

Has anyone tried this?

[SpeedGeek]

I've over-clocked my 25 MHz A3000 to 30 MHz and (even 32 MHz for short periods of time) and the SMD 030 over-heated quite easily but was never burned out. The one thing I did do was change the 1K address/data bus pull-up resistors to 3.3K. It's a fair amount of work to do this but this A3000 design bug will probably limit 030 based over-clocking to 28 MHz.

[mechy]

Can a 16mhz Amiga 3000 be converted to a 25mhz model? There are several jumpers to change and of course the crystal would have to change but has anyone done this? i am sure the 030 can take teh 25mhz but the 68881?
 
thanks

Ive ran a few 16mhz machines at 25mhz without any trouble. A heatsink is a good idea on the 030.
the fpu usually takes the overclocking in stride. i dont see 25mhz being any trouble.

We used to do the 50mhz hack on the 882' version fpu's and they never missed a beat.

mech

[desantii]

Well just finished and its working great at 25mhz.. did add a heatsink though

[SpeedGeek]

Good work desantii! I never had any doubts this would work.