Overclocking Luxo

[ClassicHasClass]

My daily driver remains my quad G5, and my regular laptop is this iBook G4/1.33 (12") I'm typing this in.

I picked up a really nice Luxo 1GHz (15" USB 2.0) that I restored and I've been using that as my backup workstation for a few months because it's quiet, it's reasonably compact, it's really cute and people love it.

However, the iBook runs rings around it. Even though the Luxo has a 167MHz FSB compared to the iBook's 133, the iBook has both a 33% faster CPU and 100% more cache (512MB compared to 256MB). I can't do much about the cache, but I'm strongly considering overclocking it to 1.25GHz, since that seems to be pretty stable based on

http://www.ethernetworks.de/imac_g4_usb2_overclocking.html

Anyone done this on an iMac G4? How easy is it to work with those small resistors? I'm not great with soldering, just simple tasks.

 

[bibilit]

Those are really tiny resistors, if you are not comfortable with soldering don't do it, the Luxo is a nice computer

 

[ClassicHasClass]

I'm also wondering if it's worth it. 1 to 1.25 is a 25% improvement in CPU speed, but I actually suspect the smaller cache is the bigger offender.

 

[CC_333]

Hi,

I don't know how compatible the two models are, but what about getting an iMac 1.25 GHz logic board and just replacing the existing 1.0 GHz one? It seems easier (and safer for the machine) to do that rather than mess with delicate resistors, and you would instantly gain that extra 25% in speed (not to mention any other improvements the faster board may have).

Just my 2 cents.

c

 

[waynestewart]

I haven't done this on the G4 iMac but I have done it a number of times on the MDD. It's not a hard thing. For removal, I use two soldering irons to heat up both ends of the resistor at the same time. It lets me do it quickly with no risk to the traces.

For adding a resistor, I use a miniature needle nose pliers to hold it in place while I solder the first end. It's pretty easy really.

Instead of adding resistors you could just use one of those circuitboard trace pens.

 

[uniserver]

when bottom half and top half connect they also make a thermal/mechanical connection make sure you clean those surfaces good and use new grease,

and if you can modify the fan with software to ventilate a little more, i would say you should be able to push her 25 to 35% with out too many issues,

please post pictures.!

 

[ClassicHasClass]

Instead of adding resistors you could just use one of those circuitboard trace pens.

It doesn't have to be a specific resistance, just a connection? That certainly would make it easier.

 

[waynestewart]

No resistance required. You can even solder bridge them if you want.

 

[ClassicHasClass]

Nice, that's very encouraging. What wattage soldering irons did you use? I'm okay at getting stuff off, I just don't want to wreck the board getting stuff back *on*. A trace pen would be perfect.

 

[Gorgonops]

Regarding the "worth" of overclocking... personally I wouldn't bother. My rule of thumb is if a computer "feels" too slow you're going to have to roughly double the speed to really notice a change. (Granted your iBook probably isn't twice as fast as the iMac, if that's your benchmark for "fast enough", but if the problem is less cache on the iMac you're not going to be able to close the gap much no matter what you do.)

Personally, when it comes to soldering I've always found getting stuff off to be a *lot* harder than putting it on. :^b

 

[uniserver]

you could always put os9.22 on it, she'll run gooooood!

 

[Mk.558]

... cache (512MB compared to 256M B) .

That's a handy cache size. A Sandy Bridge EP-8 has a cache of 20MB, so I think I'd be quite disturbed if I just bought a Core i7 power rig. :-/

you could always put os9.22 on it, she'll run gooooood!

The gent's model cannot boot 9.2.2. The last iMacs to boot OS 9 were the G4 800MHz 15 and 17" models (excluding the 800MHz OS X only model).

 

[waynestewart]

Mine are a bit of a mismatch. One's a 40 watt and the others a 25 watt.

Putting resistors back on is very easy. First I look at the two pads. If there isn't a goodly amount on it then I add more. Next I use a set of miniature needle nose pliers to hold the resistor in place over the solder pads. Then I just touch the iron to one solder pad for about 1/4 second. Then I remove the pliers and do the same to the other end of the resistor.

I think taking stuff off is potentially the most dangerous. People often do things like taking off resistors with a single soldering iron and pull off a pad.

Nice, that's very encouraging. What wattage soldering irons did you use? I'm okay at getting stuff off, I just don't want to wreck the board getting stuff back *on*. A trace pen would be perfect.

 

[ClassicHasClass]

uniserver, this one doesn't boot 9.2.2.

Yes, yes, 512K! 256K!

but if the problem is less cache on the iMac you're not going to be able to close the gap much no matter what you do.

And that's what I'm privately suspicious is the cause. I need to do a little detailed benchmarking before I come to a conclusion. If it looks like my load is mostly cache-limited, I don't think that overclocking is worth the hassle.

 

[Gorgonops]

Regarding the cache issue, I'm actually curious enough now to look something up: I went through a number of 15" G4 Powerbooks (issued at work) over the years, starting with an original 400Mhz model and ending with that last high-res DDR2 1.67Ghz model. (I seem to recall the sequence was: 400 > 667 > 867mhz > 1.5 > 1.67Ghz.) Honestly the only speed bump where I really recall noticing how much faster the new 'book was than the last one was the 867-to-1.5Ghz swap, which basically confirmed my theory that a computer upgrade should be at least "almost twice as fast" to be worth doing.

Looking at Everymac, the 867Mhz had the 256k+1MB "three level" cache architecture while the 1.5 Ghz was the straight-up 512k on-die. So apparently extra cache won't make up for a 633 Mhz clock speed deficit. ;^) But the difference probably also needs to be put into a historical context: at the time the difference between those two machines was enough that 1.5Ghz was objectively "fast enough" for, say, watching most videos, while the 867mhz was starting to get into "annoying level of frame-drop" territory with newer codecs. (It also *really sucked* at running Java, which I needed for a few things.) That was a real worthwhile/noticeable delta at the time. However, when I last worked with Powerbook G4s a few years ago (prepped a few to give away) frankly I didn't see that once-meaningful difference between a 867mhz and a 1.5Ghz anymore. Both ran 2005-vintage software and play DVDs/mpeg2s/non-H.264 mp4s okay, and both were pretty useless on the Internet once Flash got involved. I guess... trying to extrapolate my experience to what you're seeing between a 1.33ghz iBook and a 1Ghz iMac it seems to me that the list of things that would be "acceptable" on one and not the other today must be pretty short/application specific.

 

[Tron]

I have overclocked a lot of Macs. The very first time is scary, but the next ones is just a mater of being very carefull.

I have done a lot of speed test between them. Acording to my results, a 166 Mhz system bus is prefered over a L3 + L2 combination. I think you will note linear speed increase over 1.666 Mhz (if where posible in this machine). 256k of L2 is enough for a 166 Mhz system bus, even in video encoding, (where low bus speed, despite CPU and cahes is very annoying).

Sorry for my bad english

 

[mcdermd]

No need to apologize for tour English skills. They're better than some native-speakers I've read

 

[Forrest]

I have good soldering skills, but the risk of ruining a working Mac is not worth it IMHO. Before overclocking a Mac, I would wipe the hard drive and reinstall the OS, upgrade the memory and/or install a larger/faster hard drive. I have a 700 MHz G4 iMac and think the weakest link is the slow, factory hard drive.

 

[Tron]

No need to apologize for tour English skills. They're better than some native-speakers I've read

Thank you, but when you write in a non-native language which you don't know very well, you always be in risk of telling something very different of what you intended to say or even nonsenses. I like a lot this forums to fill it of nonsenses.

Sorry for the off topic.