Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Neo on December 18, 2003, 08:21:04 PM
-
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)
-
My 040 clocked @ 25Mhz is very cool. I don't even use a heatsink on it. Why is everyone so upset about its heat and all? It's fine... although I wonder if it would get hotter if I were to ever use it in an accelerator card or anything, away from my big box of chips. :-P
-
I have a 25Mhz on my BlizzardPPC, and it used to make the side of my PowerTower warm to the touch. Once I found that out I bunged a 486 heatsink and fan on their pretty sharpish.
-
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!
-
Anybody tried matching the crystals for the 040/060 and PPC chips on a blizzppc?
From some discussions with Patrik, it seems possible that faster memory access on the 680x0 side is possible if the bus speed of both CPU's is the same.
Hmm, where can I get a nice 60MHz crystal?
-
@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.
-
@x56h34
Heh, yes chips that aren't in computers tend to stay much cooler.
Anyway, my MC68040RC40 doesn't generate much heat. Although, it's clocked down to 35MHz in my Mercury and has it's built in fan. Someday I'll get around to getting a crystal and upping it to 40MHz.
I think the fastest would be the Sonnet QuadDoubler, which is a 50MHz clock, with peltier cooling.
-
@Karlos:
Here you can get a crystal:
http://www.elfa.se/elfa/produkter/en/2019471.htm
:)
/Patrik
-
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.
-
I have a 040 at 40mhz. Without cooler it's too damn hot!! You could fry eggs on it. With cooler it actually just warm! I think with an appropriate crystal and socket it would easily go faster. I've read here on forums in the past some people having their's to 45mhz if I remember correctly.
I would'd mind getting a crystal and a socket but it's damn expensive for what it is...
-
By the way, is 64mhz better than 66mhz cause it's a multiple of the bus speed or something??? :-?
-
On a mild (ok completely reversed :) detour from the topic, what's the slowest a 68040 can go? I've heard from a tech who works on PPCs that there are very definite lower limits to PPC7400 operating speeds, but is the 68040 the same?
If I REALLY wanted to, could I have an 8MHz 68040? or a 2MHz one? And would this be completely daft and pointless? :-D
dana
-
@Neo:
I saw that you mentioned using just one crystal to feed several clocklines, does this work without any problem?
@danamania:
If I recall correctly, the low voltage 68040 version supports from 0 to MAX MHz officially. Dont know about the standard 68040, though 8MHz should be ok. This would be useful when constructing something experimental on a lab-board or something similar as such an environment introduce a lot of crosstalk, signal disturbance, etc making it hard to run at high clock speeds.
/Patrik
-
@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!!! :-)
-
@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)
-
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
-
Blizzard 1240@40mhz here. I 'd like to put an 060 on it but it's very hard finding a cheap one :-(
-
Approx. 20 MHz is the lowset speed a standard 68040 can go.
68060 circuits are completely of static type IIRC and can go down to nearly 0 MHz.
-
@Jose:
www.vernalelm.com (http://www.vernalelm.com/) charges $85 USD which by todays dollar rate is a fair price.
These 68060 should be recycled and be of the oldest 01F41G mask, but it is still a 060 and the price is right.
/Patrik
-
I bought a 25Mhz Apollo 040 five years ago and have gradually upped the speed starting from 28Mhz, 33Mhz and finally 40Mhz.
I've added a heatsink between the fan and the ceramic surface of the chip and everything seems to be pretty stable considering that my CPU is running at 160% of the stated speed!
-
Hi patrik
yes right but only if you are very lucky :-)
Some of theese Vernalem 060, has problems with FPU and MMU. (and this explains the low price).
Ciao
PS- I've ordere from Vesalia 2 weeks ago, an XC68040RC33M (PGA ceramic FULL FPU-MMU with the last 40 Mhz mask) for only 12,90 EURs . . . .not delivered yet :-(
I've post to Vesalia for info about the shipment
but with no reply as usual.
Vesalia and Amiga.fr has 060 also but contact them about the specs before ordering (Vesalia 89 EUR, Amiga.fr 189 EUR)
-
Hi Neo,
Just remember, it is not wise to over-clock a processor. Most processors become unstable and untrustworthy when they are over-clocked. I recommend to anyone needing a faster processor to BUY a faster processor. Processors should only be run at their rated speed. The hotter a 68040 gets the slower it runs, so one of the secrets to gaining speed is keeping the heat down. Neo, just make sure that there is a heatsink and a good quality fan mounted onto the 68040 and it should give you years of troublefree service. Also, the MC version of the 68040 runs cooler and a little faster then the XC version. :-P
-
@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.
-
I seem to recall some 100Mhz 68040 being churned out for Crashintosch. Don't know if any one got them working on an amiga though.