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50% faster graphics Mac IIsi, Overclocking?

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i know the graphics is kinda sluggish, setting disk cache to 1024K does help!


but would changing the oscillator from 40 mhz --> 50 mhz

+5mhz Speed it up to where i would notice?


Because i was considering taking the 50mhz Oscillator from my Quadra 700


and changing that one to 60mhz, i guess is the thing to do, i hear too much over 30 mhz and you can run into issues…


my better judgment says i should leave the quadra 700 alone… but the Mac IIsi i don't care as much about,

anyone have a spare 50mhz Oscillator laying around they can send me?

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Don't do it. You will be disappointed by the results and you've already got a "fast Mac" with your Quadra 700.


You are probably familiar with IIsi video options:

a. PDS to NuBus adapter plus any low power consumption NuBus video card.

b. IIsi PDS video card that is designed for low power.

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  • 4 weeks later...

I overclocked my Quadra 700 with a socketed 64 MHz oscillator:



The hard part was desoldering the ground pin... but otherwise it's a fairly easy procedure.


I tried slower oscillators also, for the fun of it: down to 40 MHz is OK; 32 MHz starts having video issues... 24.576 MHz or lower, no boot at all xx(


...but I no longer have the 68040 on it; it currently runs on a PPC601 accelerator card on the PDS, which gets the 64 MHz speed as a bonus ;)

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  • 4 months later...

WOW, Overclocked the IIsi to 29mhz!!!!


Just threw a 57.2832mhz oscillator in there, removed the 40.000 mhz one.


And my god this thing sails! its fast, check out the vampire video!! look at the pictures ... even the 20mhz FPU is faster!






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yeah the video went from 26 to 66, its fast and smooth now! and @ 66 its 24 points higher then the IIci!!!

40% increase in video! but I'll take it!


the cpu went form 31 to 46, and @46 its 9 points higher then the IIci!!!!!


even the FPU went from 14 to 20.1 still 2.7 points higher then the IIci, for the FPU.


I tested the Local Talk it works very fast, and reliably I copied over a 5 mb file.


The only thing I have not checked is to see if it will still boot from a floppy.

The floppy does work, saved my simcity game to it, no problem.


Scrolling around in simcity is where you really notice the speed. and Scrolling up and down when browsing files, in finder.

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Yes , I noticed some heat with the VLSI IC's as-well.

As you can see from the picture, I had 3 sticky heat sinks left, so I popped them on.

The cpu generates more heat then the VLSI's IC's.


Unlike the LC-III OC to 33mhz, VLSI, acutely made more heat then the cpu.

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Been using this on and off for the weekend, its solid.


However I still have not tested it to see if it will boot from a floppy!

(I just remembered this) I'll try to remember to test this tonight.


This OC with Dougg3's Rom Simm, wow! is all i can say.

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  • 9 months later...

ok lol had to de solder all this and re-do it up a little better.


they didn't have any oscillator sockets at the store.

but taking a closer look at these IC sockets, looked like i could make it work.

[attachment=2]Screen Shot 2014-01-04 at 9.21.15 PM.png[/attachment]

[attachment=0]Screen Shot 2014-01-04 at 9.20.56 PM.png[/attachment]


the oscillator selection was rather POOR, all i could find was this

44.736 mhz one.

[attachment=1]Screen Shot 2014-01-04 at 9.20.46 PM.png[/attachment]


Hey at least i am set up to just pop in what ever speed oscillator i come across now.

Maybe i will do my q700 next.. and use that 50mhz oscillator in here.

And use a 57mhz one I bought in there. should kick that PPC card's speed up a little ? :)


My HAM buddy told me about this place. (Electronic Connection)

Its the only one like it still around here. Its about 30 minutes from me.

wow look at these reviews.. hahaha




is funny… they treated me pretty good.

But yeah i can tell they really don't like Novice questions in there.

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  • 2 weeks later...

ok bad news… i cannot run the IIsi at 29mhz anymore and use the PDS NIC or Nubus adaptor /w nic

the funny thing is the FPU still works…


- /w nubus adaptor in the video gets all screwy and system bombs at start up.

- /w maccon pds nic, boots up … FPU works… Nic doesnt. wont get an IP, no matter what i do.

slow it back down, it gets an ip...


the floppy did work… but now i cant boot from it. running at 29mhz.

i know it did boot disks when i first did it. odd.


When i get my crystals from olepigion i'll continue my testing.

if i can at-least get it to operate fully functional at 25mhz (50mhz oscillator) should be fine.

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