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iBook G3 700 MHZ is now 500 MHZ

Submitted by boothnut on April 20, 2008 - 3:42am. PowerPC Macs

Hey guys, I was wondering if you could help me out with this.

I recently purchased an iBook G3 700 MHZ (eBay), to upgrade and mod. I took it all apart, spray painted the panels, then replaced the Hard Drive, upgraded the RAM to 640 MB, installed an Airport card, and loaded Tiger on it.

After putting it all back together (it actually worked), I happened to look at the CPU speed in the Hardware overview and now it reads as a 500 MHZ iBook. Everything runs ok, except for Quicktime movies (very choppy).

I'm 99% sure this was a 700 MHZ model, when I hacked it open. I mean, it has 16 MB of video RAM, which is indicative of only 600-700 MHZ models.

I read around the web and found some information about power PCs throttling back when not being utilized fully. I'm pretty sure that is not what is happening here, since the 500 MHZ display never differs, regardless of what tasks I perform.

What is going on? Did I damage something? Do I need to update some system profiles? Is this just a glitch?

I would appreciate any feedback on the matter...

Aaron

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cwsmith's picture

Are you *certain* it was a 700?

Submitted by cwsmith on April 20, 2008 - 4:45pm.

Lift up the keyboard and check the system spec on the sticker inside. It should tell you the processor speed, along with the RAM, HD, and optical drive stats the machine shipped out with from the factory.

If you like, send me a private message with the serial number (don't post the SN in a public forum), and I'll check it against Apple's database for the machine's original specs.

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700 MHZ confirmed

Submitted by boothnut on April 20, 2008 - 5:34pm.

Yeah, I should have checked that earlier.

However, it is (indeed) a 700 MHZ model.

How bizarre is this situation?

Any suggestions?

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iantm's picture

Verify that the serial number

Submitted by iantm on April 20, 2008 - 5:37pm.

Verify that the serial number on the logic board - available by clicking on where it says the version in "About this mac" is the same as the one on the plastics. Also, verify the specs in Apple System profiler. It wouldn't shock me if a 500mhz board found its way into a 700mhz machine. (well, a 12" anyway - as there was no 500mhz 14")

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They all match. I'm sure

Submitted by boothnut on April 20, 2008 - 5:58pm.

They all match.

I'm sure I checked the speed after purchasing the iBook. It used to read as 700 MHZ. I would have returned it otherwise.

I'm at a loss. I updated everything. There is still no change.

Is it possible to knock off 200 MHZ by jostling the hardware? That sounds ludicrous to me.

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cwsmith's picture

Force rescan of the system bus

Submitted by cwsmith on April 20, 2008 - 6:02pm.

• Shut down the computer. Remove any extra RAM from the expansion slot (or add a stick if there's none there).

• Restart the computer. When the system notices the RAM configuration has changed, it will scan the entire system for any other changes. Maybe it'll recheck the processor too.

• Report back with your findings.

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I popped out the 512 MB chip

Submitted by boothnut on April 21, 2008 - 2:21am.

I popped out the 512 MB chip and restarted.

The speed was listed as 500 MHZ.

I popped the chip back in.

The speed remains 500 MHZ.

This problem must be software related, right?

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dankephoto's picture

reset PRAM and OF, boot to installer CD/DVD

Submitted by dankephoto on April 21, 2008 - 3:57pm.

Boot holding the cmd-opt-P-R keys to reset the PRAM - Mac will chime and restart

and

Boot holding the cmd-opt-O-F keys to boot to the OpenFirmware prompt.

type reset-nvram
type return
type reset-all
type return

Mac will chime and restart

Also, have you booted from an installer CD/DVD and run System Profiler, what's it say?

dan k

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I'm learning all sorts of g

Submitted by boothnut on April 22, 2008 - 2:51am.

I'm learning all sorts of great stuff from you guys.
I really appreciate all of your help and suggestions.

I reset the PRAM and the firmware stuff--still no change.

I don't have a Tiger installer disc for this laptop. I do have one for my iMac G5, but I'm pretty sure it's system specific.

Anyone else want to take a crack at this?

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Perhaps you accidentally knoc

Submitted by bin_jammin on April 22, 2008 - 3:44am.

Perhaps you accidentally knocked off a resistor or cap on the logic board that governs CPU speed?

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That would be awfully stran

Submitted by boothnut on April 22, 2008 - 2:29pm.

That would be awfully strange, but maybe.

I probably wouldn't be able to fix it, in that circumstance.

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Does anyone know anything abo

Submitted by boothnut on April 22, 2008 - 2:33pm.

Does anyone know anything about logic board repair, related to speed-governing?

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Eudimorphodon's picture

You could try this...

Submitted by Eudimorphodon on April 22, 2008 - 5:09pm.

http://www.swieskowski.net/icook/

Assuming your iBook is one of the appropriate models with a 750FX CPU you could try forcing the CPU speed to a higher speed via software. If it works then it could be some stuck control panel option that's causing OS X to throttle the speed down regardless of the Energy Saver settings.

If all else fails, here's where the speed control resistors are. Look for damage?

--Peace

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Jon's picture

On my 600 the reported speed

Submitted by Jon on April 23, 2008 - 1:14am.

On my 600 the reported speed doesn't changed, even if I set the speed to "reduced" in Energy Saver.

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OK? Eudimorphodon, I co

Submitted by boothnut on April 24, 2008 - 4:41am.

OK?

Eudimorphodon,

I couldn't get iCook to work (I do have the correct processor), since I'm a terminal neophyte.

I'll rip it open and check the caps this weekend.

Thanks.

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