Strange behavior

chemistry_geek

Registered
I came across some strange behavior between Mac OS 9.2 and Mac OS X.

I have a Blue & White Power Mac G3 400MHz, 640MB RAM and was bored and brave in the same moment and decided to over clock my processor. I first tried going from 400MHz to 500MHz with nothing, not even a startup. I next tried 450MHz and had success. In Mac OS 9.2 the system did run faster with absolutely no problems. In Mac OS X there was a serious Kernel Panic during the startup process (never experienced one of these before). Restarting resulted in getting a little farther in the startup process but eventually led to a total system lockup. Booting back to Mac OS 9.2 resulted in NO problems. What gives? Is Apple checking processor speeds during the OS X startup process to make sure we aren't trying to get "a little more" from our computers? Possible copy protection scheme?

chemistry_geek
 

RacerX

Old Rhapsody User
I worked on a system that had some bad RAM that would could the system to freeze while doing large photoshop processes, the same memory would not let Mac OS X boot (Kernel Panic from the start). Mac OS X needs the system to be running correctly to work, and over clocking introduces errors that Mac OS 9 won't see right away.

When companies make processors they don't set the speed at the level just before failure, they set them at the speed just before errors are introduced. At 450 MHz, your processor is running, but not error free, at 500 MHz it isn't running at all. But at 400 MHz it is running virtually error free (I say virtually because running enough large processes over and over can introduce increased heat and the possibility of errors even at factory specs).

Knowing the history of the back you processor came from help too. Like knowing that IBM was able to create 700 MHz G3s for a couple years when Apple would only buy 500 MHz and below because the G4s were at 500 MHz means that some of the iMacs (350/400/450/500) could be overclocked with very little risk because Apple was forcing them to be underclocked to not hurt G4 sales. When the Blue and Whites were the main product, 500 MHz was the upper limit and they would only turn up in production less than 25% of the time (based on the fact that all G3 processors of a given batch are made from the same die, but some are just better than others at handling faster clock speeds).
 

MacCheetah3

Registered
Hi
Correct the processor isn't made for that and OS X pushes your computer a hell of a lto harder than the previous OS's. So sorry I guess you're stuck thought that little MHz jump won't show tooo much anyway.
 

dcantrel

Registered
Overclocking ANY G3 or G4 will normally cause a kernel panic in X due to timing and syncing issues with the bus. When you overclock the processor you are changing the bus timing ever so slightly but it is enough that X does not like it. X reguires almost ruthless precision from your hardware at all times.
 

chemistry_geek

Registered
About two weeks ago I had to replace my logic board. The reason for replacing the logic board was due to static discharge. I was plugging in the keyboard to the USB port without the computer being plugged into the outlet and GROUNDED. As I was pluggin in the keyboard under my dark desk, I saw some little blue static discharge sparks. I didn't think anything about it until I turned on the computer saw absolutley NOTHING! Needless to say, I paniced. The univeristy I attended will diagnose any PC or Macintosh and then recommend who to contact for replacement parts. The repair people checked every card in my system and said it was likely the logic board and that it wasn't going to be cheap. I was given the name of an excellent Macintosh repair center: AllMac (http://www.allmac.com). I requested a Blue & White G3 logic board and was sent a PowerMac G4 logic board. Since I wasn't sure if the processor was bad, I also ordered an IBM 500MHz G3. The logic board was $400, the G3 processor was $300. Since then, I have overclocked the 500MHz G3 to 550MHz and it worked flawlessly (failed at 600MHz). I returned to the original 500MHz clockspeed since AllMac shipped me the same 400MHz heat sink. I had to purchase a processor fan just to make sure the 500MHz chip doesn't fry with a 400MHz heatsink. Everything works very nicely except the system is louder with that extra fan running.

If I knew they were going to send me a G4 logic board, I would have purchaed a G4 processor, oh well, my next system will be a FAST-ASS G5.

My New FrankinMac: Blue & White G3 case, G4 logic board, IBM 500MHz G3, 12GB UltraATA, 18GB UltraSCSI, Adaptech 2930 UltraSCSI card, LaCie SCSI CD-RW, Logitech 3 button wheel mouse, 768MB RAM.
 
Top