Fastest 040 CPU?

[Neo]

Hi fellow Amigans,

What is the fastest anyone ever clocked a 040 cpu?

These are my current tests with two different 040's

XC68040RC25A
25MHz (No heatsink) - Can be used to boil eggs
33MHz (Heatsink and fan) - Body temp (very stable)
40MHz (Heatsink and fan) - Crashes if datacache turned on

XC68040HRC25M
40MHz (Heatsink) - Lika a hot day in Sahara (no problems so far)

My guess is that the latter one could be clocked up even a little
further. Especially when I put the fan back on.

So, is there anyone with a 50, 60 or even 66MHz 040 Amiga?
I'm eager to hear! (060's are just to expensive)

[Neo]

It appears that there is a large difference in heat generated from
different 040's.

The first one in my listing was from a GVP board.
Originally I used it together with the original Quantum harddrive
which together generated so much heat that you seriosly got 1st degree
burns if you put your hand behind PSU fan. I used to call it the
plasma went.

Measuring the temp of the other CPU i test at 40MHz is actually only
at 45°C, so it's just like a warm day in Tikrit I think.

Be happy you got one of the good ones!

My CyberstormPPC board actually made my machine to run cooler. But the
worst heat sources are old crappy harddisks. Beware of those!

[Neo]

@Karlos

Did it on my CyberstormPPC! Upped the System/040 osc. from 50MHz to
60MHz and I can tell FroggerNG played back movies a helluwa faster.
(approx. 5 times faster)

Also, tried using a single 66MHz osc. to feed both CPU's but the boost
was just like 2 times or so over using twin 60MHz osc. (Still worth
it)

From what I found out it seems the most important part is the clock
the 68k CPU as fast as you can manage, since the 68k is the one that
feeds the PPC and so the PPC never gets faster than the 68k can feed
it with work.

[Neo]

Well, thanks for the answers.

I did some research and it appers that people that do some serious
overclocking don't do more than 40MHz for the RC25 models. I haven't
seen anything about overcklocking RC40 models. But that might be that
not many people thinks the RC40 is worth the price.

Tried 50MHz but it appeared my 100MHz oscillator was broken because it
got very hot and nothing else.

I'm thinking of trying to find out what the maximum speed is but
oscillators are expensive so I want to limit the range of frequencies
to test with. That was the reason for my questioning.

[Neo]

@Patrik

Yes! I put a 66.667MHz osc. in the center slot (System/68K) of my PPC
board and made a wire to the PPC oscillator slot.

No strange crashes! But on the other hand haven't got them since I
started overclocking. My Amiga likes going fast!!! :-)

[Neo]

@Jose

Might depend on what board you have. For the CyberstormPPC board it
appears that the only thing that matters is to use as high rates as
possible. Could be different for 060's though. (They use different
clocking)

[Neo]

Aarg! I just succeded with the infamous breaking of coppertracks on
my PPC board. :-x

These surface mounted resistors are just to small. Should have used a
torch instead. Usually gives better result as long as you don't put
the board on fire.

Well, now I have a nice little copper wire instead of the original
track. Looks really amaturish!

But hey, isn't that how a true Amiga should look like! :-P

[Neo]

@FlagshipAmigaLover

Yea, you are right about that it's not safe to run a CPU above it's
rated speed. I have fitted a fan on the heatsink to try to keep it
below 40°C.

Well, about buying a faster CPU! I would gladly do it if I just could
get hold of a retailer selling a 2 GHz 68060 CPU for about $100. I
just think $300 is a little to much for a 50 MHz 68060, which is the
one I would like to have.

And anyway, overclocking is a sport on it's own. If I blow the CPU
I'll just have to put a new one in! 8-)

About the difference between the XC and MC versions. This also applies
for the 68060 CPU's. I'm not sure but I'll think MC is the industrial
rated components.