[jkehn]

Recently I overclocked my powermac g3 from stock 350 mhz to 400 mhz. I was hoping for more than just one 50 mhz jump, I attached a new heatsink with a dedicated fan on it. I thought that might let me make a greater jump, but it didn't. Do any of you experienced overclockers know how to do this? Also, is it safe to overclock the bus speed to say 133mhz are there precations I should take? Can I damage anything? Any input would be appreciated.

[Platypus222]

Originally Posted by jkehn

Recently I overclocked my powermac g3 from stock 350 mhz to 400 mhz. I was hoping for more than just one 50 mhz jump, I attached a new heatsink with a dedicated fan on it. I thought that might let me make a greater jump, but it didn't. Do any of you experienced overclockers know how to do this? Also, is it safe to overclock the bus speed to say 133mhz are there precations I should take? Can I damage anything? Any input would be appreciated.

400mhz is the safest jump from 350mhz and easy to do without much risk, but I got my B&W to 450mhz easily with the same bus speed. I never tried to change my bus speed, I read that was not a good thing to do, but maybe others might have more info on that. There's a whole thing on XLR8 about this.
Good luck.

[Lateralus]

You can't set the bus speed on the B&W through the jumper blocks.

[Platypus222]

Originally Posted by Lateralus

You can't set the bus speed on the B&W through the jumper blocks.

well XLR8 says you can, but they don't recommend it. I never tried. Maybe your right.
450 compared to 350 did make a significant improvment though so no biggie.

[jkehn]

i appreciate your input, guys. thank you. i was getting worried no one would respond. what i'm really looking for is someone who's tried it. i'm worried about frying my ram or something.

[Waragainstsleep]

I think they tend to get unstable if you up the bus speed. Oh and the answer is yes: you can damage your mac by overclocking it. In theory you could melt the CPU, or if you OC the bus, any chip on the board. Doesn't tend to happen so often though, they usually just don't boot if you clock too high. Most are OK when you clock them back down again. But you've seen that happen already.

[bowwowman]

Best advice is to NOT mess w/ the bus speed. 99.9% of the time, it will cause all sorts of BAD things to happen to other components. Been there, done that

O/C'ing the cpu, now thats a much safer operation, however, not 100% guarenteed either. The chips tolerance for running faster varies with each individual chip. Some, like my friends', will not go more than 50mhz over it's rated speed w/o locking up the entire machine.

My B&W, OTOH, easily went from 350mhz to 500 notta problemo (with a small heatsink fan on top)

And a year later, when I installed a G4 upgrade, it easily went from 550 to 650 notta problemo either. Got it to run for a while at 700, but soon saw stability problems, and backed it off to 650, where it has been running great for over 3.5 yrs now.....

do the o/c in 50mhz increments until you see stability suffer, then back it off by 50mhz and be happy you got a FREE speed boost!

[jkehn]

If I was to slightly lower my bus speed do you think that i could get another 50mhz off the processor?
Also, would that make my computer faster overall?

[Lateralus]

The speed a CPU can handle has nothing to do with the bus. It all depends on the yield.

[jkehn]

What exactly do you mean the yield? Could you be more specific please?

[jkehn]

Does anyone out there know what specifically limits how far you can pust the processor?

[bradoesch]

Originally Posted by jkehn

What exactly do you mean the yield? Could you be more specific please?

A 400 MHz G3 is identical to a 450 MHz G3 except it couldn't run reliably at 450 MHz. If it still couldn't run at 400 MHz they'd test it at 350 MHz and mark it as that.

If the plant had many orders for 350 MHz G3s they would even take processors that were tested for 450 Mhz and mark them for 350 MHz.

I have a 450 MHz Pentium 3 system that's been running 24/7 for months at 600 MHz. That's like taking a 350 MHz G3 and overclocking to 466 MHz. Anyway, in order to overclock I had to up the bus speed since the multiplier on the CPU is locked. So the bus speed went from 100 MHz to 133 Mhz. That means my PCI and AGP bus is overclocked, as well as ATA (hard disks and optical drives.) I think I'm rambling now.

[darthslacker]

The big thing with overclocking the bus is what else gets overclocked as a result besides the Processor and RAM. On a B/W G3, the main thing you would probably have problems with is the PCI bus. Many PCI cards don't like that

[Waragainstsleep]

I bet OC'ing the RAM and memory controller would cause bother as well. Those old 106s are a pain at normal speed.....