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| Upgrading to Full 68040 - Heatsink Needed? |
Posted by: Guybrush3pwood on 2016-04-17 20:35:57
I plan on upgrading my three Macs (LC575, Performa 575 and 6115CD) to full 68040s. I've seen a few places claim you need to paste and heatsink your processor. Is this correct?
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Posted by: Unknown_K on 2016-04-17 21:19:25
Yup.
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Posted by: mrpippy on 2016-04-17 21:27:41
Really? I had a 660AV and don't remember any heatsink on the '040, and can't imagine there be much heat difference between the LC040 and 040. I also had a 6116CD and there was a small heatsink on the 601.
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Posted by: rsolberg on 2016-04-17 21:36:34
Unless you have a different logic board in your 6115CD, you'll find it already has a 60MHz PPC 601 with integrated FPU soldered to the board. As for the two 575s, it's strongly recommended to run full '040s with heatsinks as they produce significantly more heat than the LC040 they'll be replacing. Some very late examples of the 68040 have improved thermal characteristics and run well without. I run an MC68040 with mask code L88M and it runs barely warm to the touch without a heatsink. That mask was only introduced in 2002, though. The previous revision introduced in 2000, the K63H will probably be fine without too. Any XC68040 is earlier and needs a heatsink. An MC68040 with mask code E42k will probably require a heatsink.
See here:
http://newsgroups.derkeiler.com/Archive/Comp/comp.sys.m68k/2006-01/msg00000.html
EDIT: Mr Pippy, your Quadra or Centris 660 ran at 25MHz where the OP's 575s will run at 33MHz. The full 040s get very toasty at the higher frequency. Unlike an Intel 486SX and DX, where Intel disabled the FPU for the SX models, the 68LC040 and 68040 are distinct designs. The full 040 has far more transistors on die due to the fpu, which leads to far more heat.
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Posted by: mrpippy on 2016-04-17 22:21:10
Thanks for the info, that all makes sense. I have a Q605 and a Mystic CC, and a full 040 I want to put in one of them at some point.
I just took a look at the Quadra 650 and 840AV logic boards, both with 33 MHz 040s, and they both have heatsinks.
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Posted by: uniserver on 2016-04-17 22:44:30
well it depends… if you are running the cpu @33mhz and not over clocking it in your lc475 and you get ahold of a quadra 840av cpu witch is 40mhz cpu. i would say you could use it with out a heatsink.
however if you put a 25mhz Quadra 630 or q700 full cpu in there… and are running it at 33mhz yes absolutely you need a heatsink.
if you found a full 33mhz cpu from a q800, i would still heatsink it.
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Posted by: Guybrush3pwood on 2016-04-18 05:29:56
So you're saying I don't need a full 68040 for my 6115CD?
Also, I guess if the answer is yes to the heatsink, then my next questions is...where do I get one from?
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Posted by: Guybrush3pwood on 2016-04-18 05:44:14
Crap, that's right. I totally forgot that my 6115 CD has a different processor entirely. I was just looking at it the other day too. Guess I'll have an extra processor for sale if anyone is interested.
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Posted by: Macdrone on 2016-04-18 05:52:43
yup the 6xxx series is powerpc so you will have a full 040 extra. It should also already have a heat sink. with a fan and mod you can speed it up also.
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Posted by: Guybrush3pwood on 2016-04-18 06:24:14
Yeah, total bonehead mistake on my part. Ah well.
So were heatsinks ever made for the full 040? I searched ebay but didn't find anything.
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Posted by: 360alaska on 2016-04-18 08:01:35
Search ebay for "Northbridge Heatsink" or "Chipset heatsink" and get one of those...
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Posted by: Macdrone on 2016-04-18 08:07:46
the quadra 950 had a clip on heat sink, have to have tabs on the plastic cpu holder tho. I just used thermal paste and then a drop of super glue in each corner to hold it in mine.
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Posted by: Floofies on 2016-04-18 08:14:55
Mirroring what Uni said here, the 68040 doesn't require a heatsink unless you run it at or above 33Mhz.
So were heatsinks ever made for the full 040? I searched ebay but didn't find anything. Your 68040 uses a PGA-179 socket, so get a heatsink for that socket. Or measure the processor and find a stick-on heatsink of the same size. Or, you can order several smaller heatsinks that geometrically fit on top of the processor.
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Posted by: Guybrush3pwood on 2016-04-18 09:15:26
Thanks, I plan on running it at 33mhz, which is what they run at stock, correct? Do I need to make any adjustments via the board or is it just plug and play?
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Posted by: Guybrush3pwood on 2016-04-18 09:23:11
Oh, I see they also run at 40. Maybe I'll do that. Should a heatsink be enough or should I be looking at something with a fan as well?
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Posted by: Floofies on 2016-04-18 11:06:25
You definitely don't need a fan on the processor. The chip is around 47x47mm, so something like this would work fine.
Funnily enough, I've seen a few clueless Q/A sites recommending HUGE heatsinks like this for a 68040. Really made me laugh!
By the way, I recently accidentally ordered a few extra heatsinks for the Valkyrie chip. If you want one (or a few) and can pay the cheap shipping/mailing cost, I can send some to you.
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Posted by: Macdrone on 2016-04-18 11:31:30
A fan? have not seen a fan on an 040 yet on purpose. All pretty tall heat sinks the same full rectangle size as the chip. a fan cant hurt but not seen one myself.
on the powerpc yes but not the 68k's
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Posted by: Guybrush3pwood on 2016-04-18 11:32:26
Are they the same size? I'd be down. Send me some pricing.I'd need two.
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Posted by: Unknown_K on 2016-04-18 13:06:11
I have a pair of Radius Rocket 25's and they have a heatsink even with 25mhz 68040's.
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