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| Upgrading to Full 68040 - Heatsink Needed? |
Posted by: Guybrush3pwood on 2016-04-18 21:54:28
What? lol
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Posted by: Macdrone on 2016-04-18 22:15:49
max out the memory and the cpu to a full 68040 for the fpu will help, but if you can boost cpu speed from the link i put up the 25 mhm to 33 mhz is big, and so is 33 to 40 mhz. I took my 638CD to 40 mhz and its faster than I ever remember and with the full fpu everything is quicker.
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Posted by: rsolberg on 2016-04-18 23:36:17
Wolfenstein 3D can take advantage of the FPU. Apparently it makes a difference in playability on the 575: https://68kmla.org/forums/index.php?/topic/6185-lc575-68lc040-cpu-info/
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Posted by: Guybrush3pwood on 2016-04-19 07:09:27
Nice! I'm getting psyched!
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Posted by: olePigeon on 2016-04-19 09:53:42
Warlords II takes advantage of the FPU. Faster random map generation if you have one.
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Posted by: johnklos on 2016-04-19 14:35:33
Older m68040s, which are labelled "XC", require heat sinks for speeds faster than 25 MHz and really should have a heat sink for 25 MHz. They're fine at 20 MHz. They are made with a 0.8 um process.
Later m68040s, labelled "MC", use a newer and smaller mask (0.65 um) and therefore take less power. They're usually fine at 25 without a heat sink but should have one at 33 MHz or faster.
The last m68040s, which have masks K63H or L88M, use a .057 um process and run coolest. They can be run at 40 MHz without a heat sink and run reliably at 50 MHz with a heat sink.
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Posted by: rsolberg on 2016-04-19 15:30:58
Nice concise explanation, johnklos.
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Posted by: olePigeon on 2016-04-19 16:33:04
What's the overclockability of a MC680RC40? Guess it has the .065µ mask.
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Posted by: Macdrone on 2016-04-19 20:13:41
the lowend mac site doesnt show chip limits but states most anything above 45 mhz starts messing with ports.
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Posted by: johnklos on 2016-04-20 00:38:07
Most original m68040s can run up to 40 MHz without problems because they're all made the same - the chips labelled 40 MHz from Motorola were tested and confirmed good at 40 MHz, but internally they're no different than the 25 and 33 MHz parts. Some of them, when properly cooled, can run up to 50 MHz.
The 0.65 and 0.57 um (typo above - it's 0.57, not .057) masks can pretty much all run at 50 MHz with proper cooling. I'm running a few early XC chips in NewerTech Quadra Overdrives at 50 MHz and got a K63H mask chip for one of them, and it runs fine without a heat sink but with a small fan at 50 MHz.
Therefore, I think overclocking a newer mask is more or less limited by the rest of the system, not by the chip itself.
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Posted by: olePigeon on 2016-04-20 08:34:44
OK, thanks. I have a Daystar Turbo 040 with a 40MHz rated MC68040RC40 with the .65 mask. It already has a heatsink, but I think I'm going to remove it, apply some thermal grease, then put a new heatsink and a fan on it. I'd like to get 50MHz on it. 🙂
The Turbo 040 has a lot of extra electronics, so I'm hoping it won't suffer the same issues as simply overclocking the CPU directly on the motherboard. Not sure what the terminology is for that. Separate CPU clock from the BUS clock?
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Posted by: olePigeon on 2016-04-20 08:36:50
Speaking of removing the heatsink... it's like it's glued on. What's the best way to remove it? Or should I just leave it and add a fan?
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Posted by: Macdrone on 2016-04-20 09:30:46
just leave it on and put a fan. The radius rockets used the same stuff. Its really stout and all I ever accomplished was taking chips out of the chip.
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Posted by: johnklos on 2016-04-20 13:52:02
Luckily, the speeds on the Daystar aren't coupled with the speeds on the motherboard, so you won't run in to any problems with ports not working or anything like that.
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Posted by: olePigeon on 2016-04-20 14:30:10
Oh, goody. 50Mhz here I come! 😀
Still, too bad there isn't a safe way to remove the heatsink. Would be pretty awesome to watercool the CPU and see how far I can overclock it.
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Posted by: Unknown_K on 2016-04-20 14:32:19
You might run into issues with the cache on the Daystar if it is built in. The 040 I have that is overclocked has no cache board attached.
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Posted by: olePigeon on 2016-04-20 17:37:43
Looks like it. I stuck in a 25MHz crystal and my machine immediately gets death chime. 🙁
*sniff*
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Posted by: dr.zeissler on 2016-04-21 14:55:07
I put a full 68040 with heatsink! in my LC-475 but Wolfenstein is way to slow on that machine especially in high-res-modes.
The smallest windows is good, but too tiny in my opinion.
Doc
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Posted by: Macdrone on 2016-04-21 15:43:34
does the 475 have the resistor change you can do to get 33 mhm? you should look at that page. its super easy.
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