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| Click here to select a new forum. | | Overclocking a Quadra | Posted by: bigmessowires on 2017-06-13 18:30:14
Has anyone ever overclocked a Mac Quadra to 40 MHz or higher? How was the experience, and did everything still work correctly afterwards?
I have a sudden and completely irrational desire to possess a 40 MHz 68040 Mac, but the only true example is the 840AV which is too bulky for my taste. I've been reading about overclocking and getting ideas... http://lowendmac.com/2014/overclocking-the-mac-quadra-series/
| Posted by: Themk on 2017-06-13 18:46:57
Quadra 630 (Once a Performa 638CD, but a full 040 fixed that problem) owner here.
Moving the two resistors required was pretty easy to do, they were SMD. This causes the clock generator to now output 40MHz, which overclocks the CPU, as well as the video chip, and the system bus, and a few peripherals integrated in to the ICs. I did add for good measure a heatsink to the CPU and the video chip. Everything, and I mean everything works (I believe that this board was originally designed for 40MHz, then later crippled by Marketing). SCSI, ATA, floppy drive, ADB, serial, audio, PDS, Ethernet, etc. And, to top it all off, I inadvertently ended up doing a stability test with it, running NetBSD for over 24 hours in this 40MHz config, compiling packages the whole time. No problems whatsoever.
| Posted by: bigmessowires on 2017-06-13 19:43:26
hmm... (searches eBay for 63x motherboards)
It's funning how 40 MHz 68040 is still "fast" in my mind, even though it's orders of magnitude slower than stuff I think of as "slow" like Intel Atom cpus. I guess it's all relative.
| Posted by: Themk on 2017-06-13 19:50:52
Good luck on your search for 63x motherboards. I like them.
40MHz 68040 is fast on the software it can run. System 7.1.2 on this, and with a good productivity package is fantastic. With the Atom, it's not very fast for the software it can run, that's probably the primary difference.
| Posted by: Trash80toHP_Mini on 2017-06-14 08:20:10
It's funning how 40 MHz 68040 is still "fast" in my mind, even though it's orders of magnitude slower than stuff I think of as "slow" like Intel Atom cpus. I guess it's all relative. Absolutely, perceived CPU performance is probably almost directly proportional the revision levels of the applications that are possible to run under whatever compatible OS is installed on the system. IOW, anything that'll run on a Quadra is going to seem blazingly fast with that 7-15MHz bump in clock rate on whatever you've become accustomed to funning.
That's why I've almost always run an older rev. of Illustrator alongside my clockwork upgrades which offset feature bloat induced perceptions. Sometimes even a couple of revisions back were installed on what were inevitably obsolescent, used Duos running under 7.5.5. The longer term use 68000 code limited PowerBook100 and then the Duos never seem all that slow in their day and still don't as a result.
p.s. "funning" retro-gear is a wonderfully delicious typo if unintentional, teh 68KMLA's lexicon has been appreciably enriched. [😉] ]'>
| Posted by: Floofies on 2017-06-14 20:25:05
I have a 630 with the 40MHz resistor change, including heatsinks for CPU/Valkyrie. It runs 7.6.1 quite well with no issues.
| Posted by: johnklos on 2017-06-15 09:23:31
Someone was selling Performa 636 / Quadra 630 motherboards for cheap not too long ago. It was the one that has two SIMM slots, and I got one so I could have 196 megabytes of total memory. I downclocked it to 25 MHz so I could run a NewerTech Quadra Overdrive.
I think the system needs a new power supply, because it's no longer stable even without the Quadra Overdrive, but it's definitely worth doing.
| Posted by: Trash80toHP_Mini on 2017-06-15 10:22:52
Got linkage?
| Posted by: johnklos on 2017-06-15 22:52:44
No, unfortunately. I may've even learned about it here, but I can't seem to find the original links. Then again, they seem pretty cheap on eBay.
Here's how I added the NewerTech Quadra Overdrive:
http://www.ziaspace.com/~john/quadra630/
| Posted by: BadGoldEagle on 2017-06-16 01:52:26
You could also buy a 40Mhz Turbo040 and stick it inside one of your SE/30s... That's what i'd do, but I'm a Compact fanatic.
| Posted by: Cory5412 on 2017-06-16 07:12:03
I don't have my 610 or my 475 on hand to compare, but I will say that I've always personally been pleased with the performance on the 840. I don't know if it's really all that better than the 33MHz systems, but it's certainly good in its own respect, and at software that doesn't need or have a lot of ppc acceleration, mine feels faster than a 6100/66. That could be due to the disks on each system though.
The 475-605/610/660/650/700/800/900/950 (every desktop 040 not already mentioned) can also all easily be overclocked. At least one person on the forum who is also on the IRC channel has a 650 they put either a 33 or 40MHz chip in then used an old overclocking tool (whose name I forgot) to get to 44MHz.
I've heard in a few places of people getting 50MHz on those kits. I don't know individually how any particular system would react to that. My guess is that the 650/800/950 and 840 would react best, since they're designed initially around 33MHz chips, but the whole design is probably such that any system could run at any speed.
A 40MHz Q700 would be really neat.
| Posted by: bigmessowires on 2017-06-16 21:19:14
I do like the Q605, and I owned one back when it was a current machine. But it looks like it only overclocks to 33MHz before it get unstable.
The Q630 and its various siblings seem to be nice machines with good overclocking ability and that aren't too big. I'm very biased against big and bulky computers. I have limited space for all my retrocomputing stuff, so everything needs to justify itself on a usefulness per cubic centimeter measure. 🙂 Of course none of my gear is truly useful, if I'm being honest, so maybe it's better to say -- provides more opportunities for tinkering.
Part of my motivation is to examine how the floppy disk interface behaves on the fastest 680x0 Macs. During some communication with the floppy drive, the Mac essentially treats it like a 16x1 bit register file. The "access time" of that register file isn't documented anywhere that I'm aware of, and in practice it varies with the execution speed of the Mac running the floppy driver code. I want to try to measure it, so I can brainstorm what other interesting things could potentially be hooked onto the floppy port similar to what I did for the Floppy Emu disk emulator. Maybe I could learn the same information by looking at the driver code in some 040 Mac's ROM, or running under emulation with MESS? But whatever flimsy justification I provide, the truth is that a fast 040 Mac just seems like it would be cool to add to the collection. 😉
| Posted by: BadGoldEagle on 2017-06-17 01:40:15
I do like the Q605, and I owned one back when it was a current machine. But it looks like it only overclocks to 33MHz before it get unstable. Apparently someone got it to work properly: https://drive.google.com/file/d/0B9rTgRm4OkZwT2FDRjhqS2YzMFk/view
| Posted by: CC_333 on 2017-06-17 06:52:38
Someone was selling Performa 636 / Quadra 630 motherboards for cheap not too long ago. Looks like I found it: http://www.ebay.com/itm/Vintage-Apple-Performa-LC-Quadra-630-Motherboard-820-0548-Logic-Board-/282030747185?hash=item41aa57ae31:g:nN8AAOSwYmZXLkBf
$19 with free shipping is quite a bargain!
EDIT: There is a catch, though: there's no CPU included :-/
c
| Posted by: bigmessowires on 2017-06-17 07:58:34
You could add a bare 68040 cpu to complete the set, but holy cow! The 33 MHz '040 is selling for $50 and up on eBay. I wonder how difficult it would be to make a drop-in 68040 clone using a custom PCB, and an FPGA with a soft-core 68040 written in VHDL. It would probably still cost more than $50, especially after considering all the time and effort, but it would be neat.
At the prices 68040 cpus seem to command on eBay, there's almost an arbitrage opportunity here: buy up unpopular or broken 68040-based systems, remove the cpus, and resell sell them for more than the original cost of the computer.
| Posted by: johnklos on 2017-06-17 10:13:50
While I love the Apollo / Vampire FPGA accelerators for the Amigas, I think this would be more useful to more people. Since the FPGA wouldn't need to support video emulation and all that, perhaps it'd have enough space for a full CPU, with MMU and FPU, and could be a 100% compatible drop-in replacement. That'd be so nice!
| Posted by: bigmessowires on 2017-06-17 11:49:45
It looks like somebody already did this a few years ago, at least for the '060 and possibly the '040 too. But details seem sparse, and the PCB design files appear to be missing.
code: https://github.com/amigabill/fp68060
pcb: https://upverter.com/amigabill/215b379ff943fc80/FP68060/
edit: a better overview is here - http://amigabillprojects.wikispaces.com/FP68060
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