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SmileyDude · May 23, 2002, 01:52 PM

well, I'm crazy, nuts, whatever, but I want to do the dirty deed and overclock my iMac -- I've got the link on how to do it, but what I want to know is what is a "safe" speed to overclock to? Would bumping it up to 600mhz be out of the question? I'm not interested in pushing it to it's limit, just a nice little speed boost.

In addition to the OC, I plan on upgrading the HD, memory, internal CDR, and hopefully if Apple has it ready, the OS as well (10.1 to Jaguar

). That should buy a little more life for it -- until I can upgrade to a G4 iMac later on

Peder Rice · May 23, 2002, 02:58 PM

Well, 600MHz would be really difficult to pull off. However, maybe 500MHz could be done without much trouble. After you get the overclocking done, go for a 7200RPM drive. I threw one in, and so far, I have had no problems with heat, but the speed increase has been obvious. Throw in 1GB of RAM, and you'll extend the life of your iMac significantly, or at least a few months more.

Carl Norum · May 23, 2002, 03:27 PM

I wouldn't try pushing up much past 500 MHz. You won't notice much speed increase after that stage anyway - the magic bus multiplier is 5x. After that, the machine is basically just waiting faster.

Good luck!

Nostrildomus · May 26, 2002, 09:25 PM

Care to share the link ? I would love to do the same.

Carl Norum · May 26, 2002, 11:06 PM

Here you go:

<a href="http://www.bekkoame.ne.jp/~t-imai/maine.html" target="_blank">Mac Overclocking</a>

Ta da!

Kumm · May 29, 2002, 01:19 AM

If anyone has done this before i'd like to know how it turened out. I think i'm gunna try going up to 500Mhz

lebannen · May 29, 2002, 06:04 PM

Whooo. Those resistors are *small*.

Yep, this l'il old iMacDV 400 is now running at 450Mhz. I've only had it up two hours, but so far so good - no oddities whatsoever.

I initially tried pushing it up to 500Mhz for that lovely 5x multiplier - no go. First boot (upside down with all the guts still exposed!) got as far as the desktop and then kernel panicked - my first ever. Removing slower RAM chip and pushing the backside cache down to it's lowest speed had no effect whatsoever - it never got as far as the desktop again. Flipped over the resistors to 450Mhz, and it works like a beaut. Claims it's running faster, anyway - wish I had some way to test it...

A note on the resistors - they're tiny. 1mm to a side is about right. There's two different types in there - black-top (1k) and green-top (10k but tested as 3k?). These have to be moved across to keep the same rating - for example, R35/R36. Soldering them is pretty tricky - best to use a fine-tipped iron, nd just heat the resistor itself until it comes off. Reposition very carefully, and try to melt the ends into place, adding a fraction of solder if unavoidable.

So I've ended up at 450 - others can probably reach 500 without a prob, depends on your individual chip!

Peder Rice · May 29, 2002, 07:03 PM

There might also be an issue with heat. Pushing it to 500MHz might require a fan.

Todd Madson · May 30, 2002, 10:25 AM

Anyone know a site other than XLR8yourmac for overclocking a sawtooth
G4/400/AGP? The site there honestly doesn't have step by step info on
how it's done - it's more of "pull up this G4 document at Motorola,
then go here and do that". I like the japanese site here because it's matter of fact and says what to do in a step by step fashion.

I don't think I'll get more than 450 out of it but it would be nice
to try.

ambush · May 30, 2002, 06:51 PM

I'd really LOVE to overclock this old 400 Sawtooth g4.. It's kinda pitiful now, on osx.. please help us!!

Peder Rice · May 31, 2002, 11:48 AM

I think that at xlr8yourmac.com, a few people have posted overclocking their 400 Sawtooths to 500MHz. Although, my memory's been a little shaky, so you'll have to check yourself.

gdiddy · Aug 6, 2002, 09:50 AM

So from looking at bekkoame would it be possible to overclock a 350 slot loading to 450? Any info would be great.

Carl Norum · Aug 6, 2002, 10:31 AM

Originally posted by gdiddy:
So from looking at bekkoame would it be possible to overclock a 350 slot loading to 450? Any info would be great.

Sounds possible. You never know until you try.

Schmidlapper · Aug 6, 2002, 12:07 PM

I also attempted to go to 500Mhz but it did not work for me. I heard the boot chime but never got to a any screens. So I took it back to 400Mhz. To many little resisters to worry trying for 450Mhz. I used rear window defogger paint instead of the resistor and it worked fine. Easier than resoldering the resistor. I wanted to remove the cpu heatsink and replace with good paste but I think they epoxied it on. I didn't want to destroy the cpu getting it off. I settleed for adding 512Meg memory and a 7200rpm 40Gig Hard drive to speed things up.