Slashdot Mirror
Overclocking Your iBook to 600MHz
Cryptnotic writes: "The guys at Accelerate Your Mac have
figured out how to modify the motherboard on the recent Apple iBooks to get them to run at 600MHz with a 100MHz bus speed. There are
benchmarks comparing the OC'd iBook to some regular Apple desktop machines. However, what I am wondering most is how this overclocked G3 compares to the much more expensive Apple G4 Powerbook and if it makes it worth voiding the warranty." Remember, not recommended for your iBook.
As the referenced article said, it reduces battery life by 15-30 minutes. This should leave you with a realistic battery life of about 3.5 to 4 hours. My own experience is that an unmodified iBook is good for over 4 hours of editing text.
The change to battery life isn't large for two reasons. Firstly the PowerPC has dynamic power management, which makes idle time cheap. Secondly, a lot of the power consumption comes from the disk and display, which are unchanged by this mod.
This mod's been out there for quite some time, long enough for others to have performed it. As the one poster said, It didn't work for him. I've been looking on some forums (can't remember which, macworld??) but a few others have tried this, one initially had success but it was unstable sometimes, one didn't have success at all. But according to both you can still change the bus speed to 100Mhz, you'll have to switch the multiplier down to 5. Never the less the instructions are correct!
I've been looking into this because I've been wanting an ibook myself, I want to play with OSX.
For another poster that mentioned the heat issue, this is also in the article. Turns out he added a thin aluminum plate and made it cooler than before.
madcowherd
The article on xlr8yourmac.com is quite old, so I am quite surprise about the big fuzz that it generates today on '/.'.
;-)
I applied the mod about a month ago, when I decided to invest into a decent and not too expensive Linux laptop. I was quite happy with the speed of the machine, but heard from a friend of mine who knew someone at Apple who told her that the machine was originally designed for 100MHz mem bus. The only thing that required Apple to move back to 66MHz was to be able to give the machine a four hour battery run as the marketing brochures showing these figures were already printing when the tests were being ran (!)
With this in mind, I just overclocked the memory bus of the machine, because I believe that it is the main bottleneck for my application of the iBook: basically watching a DVD, playing MP3 files with iTunes (great player by the way) and being able to type a report for my boss at the same time. Yes, I can do that, but the laptop had some troubles keeping up
There are a few catches though. Part of the RAM is located on the motherboard (64MB or 128MB depending on the model you get) and the memory controller would need to be reprogrammed in theory. Not doing so can will cause some RAM not to function properly and that could be the reason for the mod not to succeed. The other problem is having the speed bus directly encoded in the OpenFirmware ROM (kinda like a BIOS thing on PC.) You can patch the value by adding an extra Forth patch in non-volatile RAM, so it's ok. This is required for some OS to calibrate properly. In my case, that didn't matter because the CPU bus was the same.
Doing this mod, I ended up using the same number of resistors. I just add to move them around. If you go for another config and end up using less resistors, keep them in a safe place as you never know what is going to happen (some people want to purchase only genuine speed laptops, so you may want to revert the mod if you sell your laptop in the future.)
I didn't add the extra metal plate as it is described in the article, because I didn't want to create to much pressure on the components or get a bended keyboard (which would have made the keys touch the screen as on the TiBook.) I just added some clear heatsink paste (the one that doesn't get messy.) I never had a heat problem with this machine, before or after the mod, even under Linux. Linux kernel is not really energy savvy on the PowerPC at this time (some bugs and lots of hacks to get the fastest context switch doesn't goes along with good energy saving.)
The last point I want to cover, is that you need to make sure you are really careful about disassembling and reassembling the unit. Aesthetic is a big thing on this particular brand of machines, so don't mess with it. I used a soft flat spoon (the kind you can find at your supermarket for mixing stuff with soft flat edges) to lever the side of the machine. I also used surgeon gloves during the all operation (no pun) and worked in the kitchen area the only place without carpet in my house. I touched the fridge before putting the gloves to make sure I didn't carry any static. You are never too careful and because this mod voids the warranty you may want to think again before going for it.
-- PPA
-- I feel better now. Thanks for asking.
Not true. The G4 also implements MERSI, instead of just MEI in the G3, making it more capable in supporting multi-processor configurations.
It also has some internal bus and FP improvements, but they're overshadowed by AltiVec and MERSI.
A quick Google search on "powerpc g4 specs" turned up this page: www.macevolution.com/g4/g4.shtml.
Now that all the necessary screws on the bottom have been removed, set the iBook bottom (exposed motherboard) down on a anti static surface (I used a large motherboard anti static bag).
Um, I'm sorry, but an anti-static BAG is NOT an anti-static surface. The bag is only anti-static when something is placed within it and the bag is sealed. This is a concept known as a Faraday Cage[1]. Placing a component on TOP of an anti-static bag does absolutely nothing.
I've been guilty of the same thing myself, I hardly ever use any type of grounding/anti-static devices when handling my stuff. But that's me, when playing with my OWN equipment. When you publish a review telling people how to take their computers apart, and then don't use the proper precautions, that's just negligent.
[1] - A device that is a conductive enclosure that terminates anelectric field on the exterior so that no field exists on the inside of the enclosure.
der dee der.
According to IBM's datasheets on the 750CX and CXe (the iBook uses a 750CX IIRC) they can use up to a 10x multiplier and a 133MHz memory bus. Theoretically IBM could spit out 1.3GHz G3s if it ever needed to. The problem with mere speed bumps on the PowerPC line is EOL concerns. The G3 750 and previous models had 60x pins and thus were compatible with older systems but the 750CX has none of these and is only compatible with more up to date systems. Thus making G3 chips for the system upgrade folks like Sonnet wouldn't bring in good returns for either company since the upgrades would only work on relatively new systems where a fair percentage of chip upgrades go into EOL Apple products. IBM, Mot, and Apple all need to keep their eyes on the future too. The G4 is able with little modification to use 64-bit instructions and a 128-bit memory bus width. The G5 will have that stuff by default so most likely Apple's going to go full fledged 64-bit Weapon X style (10.2 supposedly will come in 32 and 64-bit flavourings while >2 will be 64 bit only). That'd mean keeping the older G4 around for the low end systems and going with the G5 in the high end systems or so I surmise. I don't really see it as processor crippling but more like Apple has a much better sense of where their processors are going and what is happening with them. They're much more involved than the PC OEMs that just buy crates of whatever Intel happens to be making at a particular time. It's too bad no one will pick up the G3 to ramp the speed up to super fast levels. I really like that chip.
I'm a loner Dottie, a Rebel.
As a former Apple authorized service technician, I'd like to point out that while the warnings and such are nice (and an article that includes soldering wouldn't seem complete without it), you'd be hard pressed to find any authorized service center that would even notice the solders he was making.
Apple system repairs are done at the module level (one of the reasons it is so expensive) -- if the system doesn't start up, and you've got power from the a/c adapter, you're going to get a new logic board (unless they are doing whole-unit replacement, which is fairly common nowadays). In anycase, nobody is peering over your logic board to see that resistor R237 has been incorrectly connected to R233. The new one comes in, the old one goes in a static bag, and back to Apple via Airborne.
Not to say it won't happen that you'll get "caught" -- but it's pretty damned unlikely.