Overclocking MC68040

8bitbubsy · 28 February 2010, 07:38

I bought one of these on eBay... MC68040RC33
How high can I go overclocking it with only a thin heatsink applied? 40MHz?
Even higher?

It's for my Apollo 1240, but I don't have any 66-80MHz oscillator! Can I set it to 060 or so, so I can use a 40-50MHz one?

coze · 28 February 2010, 10:28

I suggest you don't push it any more than 33. 68040s don't take overclocking very well. With only a heat sink, you should only use it at the designated value. If it were a good 40 MHz one (l33m mask, or something like that) maybe you could overclock it.

And you can't use a 1-1 osc on a 040. You have to use a double rated osc.

alexh · 28 February 2010, 10:50

Depends if it has an L88M mask or not. These were the last ones ever made. They have a MUCH MUCH better thermal characteristic and timing capability. I read that MC68040RC40A chips with L88M mask run almost cold at their stock 40MHz speed. Compared to "boil an egg" temp for other variants.

rkauer · 28 February 2010, 18:17

An educated guess is you can go up to a bit more than the stated clock on the CPU label: 35MHz. Try with a 70MHz crystal.

After that, try with a 80MHz crystal to see if the board & CPU will be still stable. Remember to check the temperature of the chip.

As Alexh said, MC 040 part is the last revision and can run almost cool.

Oh, you can surely use a 60MHz crystal, the CPU will run at 30MHz. In a fashion of under-clock. You'll not hurt the CPU doing this, BTW.

Photon · 28 February 2010, 18:25

alexh, sell me one

Please!? Hehe. Although I don't know if the PPS-040's logic would keep up, the memory might cope if I can set enough wait states.

alexh · 28 February 2010, 19:07

The only person I know still selling them was an Italian, about 3 months ago on Ebay. He was selling them for about €40 each and had several. The auctions closed without him selling them all so perhaps you can still get one.

I *think* it was this guy. MC68040RC40A L88M

http://myworld.ebay.co.uk/mamoremio/

Secret Vampire · 28 February 2010, 19:36

I would think for any chip moderate overclocks of a few MHz should be possible, plenty of accelerators in the old days used to ship overclocked to 28/35MHz, there's a bloke on ebay selling 70.9379 and 72MHz oscillators which I'd expect to work, 40 might be a bit too much, but then 40MHz chips have been successfully taken up to 50+ in the Mac world, so there is hope.

8bitbubsy · 28 February 2010, 19:37

Do you think I can run an MC68040RC33 at 33MHz with a thin heatsink..? I really hope so.. I do have an XC68040RC40 as well, but that one gets hot as sick even with a large heatsink.

EDIT: Got a reply from the seller, the 040 I bought has these numbers:

02E42K
QQTK9804F

Is this of the "keeps cooler" type?

Fabie · 28 February 2010, 20:21

Quote:

Originally Posted by Secret Vampire

I would think for any chip moderate overclocks of a few MHz should be possible, plenty of accelerators in the old days used to ship overclocked to 28/35MHz, there's a bloke on ebay selling 70.9379 and 72MHz oscillators which I'd expect to work, 40 might be a bit too much, but then 40MHz chips have been successfully taken up to 50+ in the Mac world, so there is hope.

also in the Amiga world the 040/40mhz can be overclocked to 50 mhz using a 100mhz crystal
I did long time ago on a apollo 1240/40mhz...and was fast like the 060/50mhz
it needs a fan yes or yes...otherwise the Workbench freezes in 5 mins
The apollo 1240/50 worked fine for about 2 years then misteriously died

8bitbubsy · 28 February 2010, 20:49

Quote:

Originally Posted by Fabie

I did long time ago on a apollo 1240/40mhz...and was fast like the 060/50mhz

No it wasn't.

alexh · 28 February 2010, 21:01

Quote:

Originally Posted by 8bitbubsy

E42K Is this of the "keeps cooler" type?

It is the worst of the MC68040 parts. The two to look out for are K63H and even better L88M.

I wrote this a long time ago:

Quote:

Originally Posted by alexh

In 1989 it went into production as the XC68040RCxxyy originally a 0.8um
masks (D43B, D50D, D98D, E31F) part. These run exceptionally hot even
at 25MHz and need heat sinks all the time.

http://www.freescale.com/files/share...PCNR00274.html

In 1995 the 68040 qualified to mc status. It was shrunk to a 0.65um
mask (E42k) these parts run hot at 25MHz but _dont_ need heat sinks,
famous in MAC circles for over-clocking. There are some XC 0.65um parts
from 1992-95 with the mask E26A but I am unsure as to their
availability, heat dissipation or over-clock-ability.

http://www.freescale.com/files/share...cn/PCN5606.txt

In 2000 the 68040 was shrunk to a 0.57um mask (K63H) these run a lot
cooler than all previous parts and again do not need heat sinks at
25MHz+.

http://www.freescale.com/files/share...cn/PCN8219.htm

Finally in 2002 the last MC68040RCxxA mask was made (L88M) production
was moved back to MOS11 FAB, again at 0.57um, with increased
reliability (which should favour over-clocking even more).

There were probably intermediate mask revisions, but I have no
information (yet) about them.

Some XC chips have a H in their title, e.g. XC68040HRC33E Not quite
sure what the H stands for.

There were several revisions of some chips. The revision is the last
digit on the end of the number, some have no letter, some go all the
way to M. I do not fully understand the version numbers.

I would imagine the best 68040 to get for an Amiga would be an
MC68040RC40A with mask L88M, it should run coolest and support the best
over-clocking.

rkauer · 28 February 2010, 23:50

The xx68040RCxxM is a engineering sample. That last "M" stands for that. Don't remember where I dig this information, but it's the true.

8bitbubsy · 01 March 2010, 01:06

Quote:

Originally Posted by alexh

It is the worst of the MC68040 parts. The two to look out for are K63H and even better L88M.

But it keeps cooler than an XC68040RC40 right? And it's enough to just have a little heatsink on this MC68040RC33?

rkauer · 01 March 2010, 06:03

Yes, it is better in all respects compared to older XC counterparts.

niobyte · 02 March 2010, 14:12

I have an XC68040RC33M 02E31F QEDD9450C. Pulled straight out of an Macintosh LC 630. I don't remember it running that hot at its ordinary clock speed of 33 MHz (quite awhile ago now).

Didn't come with a heatsink either, although I do recall a fan blowing over it. I was originally going to buy an Apollo card to try it in.

All I can say is hopefully this MC model you've can handle over 40 MHz without too much heat, still better than over clocking an XC one. Judging by what alexh has mentioned already it would seem a MC68040RC40A with the mask L88M would be the best one to try and find (subject to availability).

All I can say is give it a go. If that fails, maybe try and find an LC Apple Macintosh with a 68040 and take the CPU out of it (if it breaks). Hunt around eBay for another one if that happens. You already have a spare.

I do recall some semiconductor suppliers having various Motorola 68k CPU(s). Unfortunately, most only want bulk purchasing.

Hope it all works out

alexh · 02 March 2010, 14:22

I bet if you tried to put your finger on it under load you'd burn your finger.

8bitbubsy · 02 March 2010, 16:48

Okay guys, I got my 040 40Mhz back (though the desert XC edition), and it works

So my acc is working...
It's running off the 060 5.60 boot ROM just fine, is this okay?

Waiting for an MC68040RC33 in the mail, this one will be neato!

Zetr0 · 02 March 2010, 17:02

@8bitbubsy,

I would say your 060 chip is knackered m8

alexh · 02 March 2010, 17:07

I have some untested 060's. I could send you one but I think you really need a tested part.

Zetr0 · 02 March 2010, 17:14

lol, did you ever get to sending that 060 to me alexh, I have a card to test it on,

if you want I can do a batch test for you if your short of time.

28 February 2010, 07:38	#1
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,713	Overclocking MC68040 I bought one of these on eBay... MC68040RC33 How high can I go overclocking it with only a thin heatsink applied? 40MHz? Even higher? It's for my Apollo 1240, but I don't have any 66-80MHz oscillator! Can I set it to 060 or so, so I can use a 40-50MHz one?

28 February 2010, 19:37	#8
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,713	Do you think I can run an MC68040RC33 at 33MHz with a thin heatsink..? I really hope so.. I do have an XC68040RC40 as well, but that one gets hot as sick even with a large heatsink. EDIT: Got a reply from the seller, the 040 I bought has these numbers: 02E42K QQTK9804F Is this of the "keeps cooler" type? Last edited by 8bitbubsy; 28 February 2010 at 20:22.

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28 February 2010, 10:28	#2
coze hastala vista winny vista Join Date: Feb 2006 Location: mt fuji Age: 46 Posts: 1,335	I suggest you don't push it any more than 33. 68040s don't take overclocking very well. With only a heat sink, you should only use it at the designated value. If it were a good 40 MHz one (l33m mask, or something like that) maybe you could overclock it. And you can't use a 1-1 osc on a 040. You have to use a double rated osc.

28 February 2010, 10:50	#3
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,436	Depends if it has an L88M mask or not. These were the last ones ever made. They have a MUCH MUCH better thermal characteristic and timing capability. I read that MC68040RC40A chips with L88M mask run almost cold at their stock 40MHz speed. Compared to "boil an egg" temp for other variants.

28 February 2010, 18:17	#4
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	An educated guess is you can go up to a bit more than the stated clock on the CPU label: 35MHz. Try with a 70MHz crystal. After that, try with a 80MHz crystal to see if the board & CPU will be still stable. Remember to check the temperature of the chip. As Alexh said, MC 040 part is the last revision and can run almost cool. Oh, you can surely use a 60MHz crystal, the CPU will run at 30MHz. In a fashion of under-clock. You'll not hurt the CPU doing this, BTW.

28 February 2010, 18:25	#5
Photon Moderator Join Date: Nov 2004 Location: Eksjö / Sweden Posts: 5,647	alexh, sell me one Please!? Hehe. Although I don't know if the PPS-040's logic would keep up, the memory might cope if I can set enough wait states.

28 February 2010, 19:07	#6
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,436	The only person I know still selling them was an Italian, about 3 months ago on Ebay. He was selling them for about €40 each and had several. The auctions closed without him selling them all so perhaps you can still get one. I think it was this guy. MC68040RC40A L88M http://myworld.ebay.co.uk/mamoremio/

28 February 2010, 19:36	#7
Secret Vampire Registered User Join Date: Jul 2006 Location: Birmingham UK Age: 43 Posts: 214	I would think for any chip moderate overclocks of a few MHz should be possible, plenty of accelerators in the old days used to ship overclocked to 28/35MHz, there's a bloke on ebay selling 70.9379 and 72MHz oscillators which I'd expect to work, 40 might be a bit too much, but then 40MHz chips have been successfully taken up to 50+ in the Mac world, so there is hope.

28 February 2010, 23:50	#12
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	The xx68040RCxxM is a engineering sample. That last "M" stands for that. Don't remember where I dig this information, but it's the true.

01 March 2010, 06:03	#14
rkauer I hate potatos and shirts Join Date: Oct 2007 Location: Sao Leopoldo / Brazil Age: 58 Posts: 3,482	Yes, it is better in all respects compared to older XC counterparts.

02 March 2010, 14:12	#15
niobyte AMR / HOL Contributor Join Date: May 2007 Location: Perth Western Australia Posts: 171	I have an XC68040RC33M 02E31F QEDD9450C. Pulled straight out of an Macintosh LC 630. I don't remember it running that hot at its ordinary clock speed of 33 MHz (quite awhile ago now). Didn't come with a heatsink either, although I do recall a fan blowing over it. I was originally going to buy an Apollo card to try it in. All I can say is hopefully this MC model you've can handle over 40 MHz without too much heat, still better than over clocking an XC one. Judging by what alexh has mentioned already it would seem a MC68040RC40A with the mask L88M would be the best one to try and find (subject to availability). All I can say is give it a go. If that fails, maybe try and find an LC Apple Macintosh with a 68040 and take the CPU out of it (if it breaks). Hunt around eBay for another one if that happens. You already have a spare. I do recall some semiconductor suppliers having various Motorola 68k CPU(s). Unfortunately, most only want bulk purchasing. Hope it all works out

02 March 2010, 14:22	#16
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,436	I bet if you tried to put your finger on it under load you'd burn your finger.

02 March 2010, 16:48	#17
8bitbubsy Registered User Join Date: Sep 2009 Location: Norway Posts: 1,713	Okay guys, I got my 040 40Mhz back (though the desert XC edition), and it works So my acc is working... It's running off the 060 5.60 boot ROM just fine, is this okay? Waiting for an MC68040RC33 in the mail, this one will be neato!

02 March 2010, 17:02	#18
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@8bitbubsy, I would say your 060 chip is knackered m8

02 March 2010, 17:07	#19
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,436	I have some untested 060's. I could send you one but I think you really need a tested part.

02 March 2010, 17:14	#20
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	lol, did you ever get to sending that 060 to me alexh, I have a card to test it on, if you want I can do a batch test for you if your short of time.

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