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zmttoxics
May 28, 2009, 04:11 PM
Well, using some guides (check bottom of post), I did some experimenting with my old G4 Sawtooth to see how fast I could run its lame 400mhz cpu. Ultimately, my goal was to make Quake 3 playable at a resolution other then 800x600. These tests were all done with PC-133 ram (896MB), running 10.4.11.

Starting specs:
400mhz (4x100mhz)
Xbench cpu score: 19.9

1st overclock (with 400mhz cpu):
500mhz (5x100mhz)
Xbench cpu score: 29.3
Note: This was incredibly unstable.

In the process of moving to 450mhz on the 400mhz stock cpu, one of the jumper resistor solder pads came off (lame 10 year old glue). So, I went on ebay and got 5 450mhz G4 cpus for 50$ CDN after shipping. One of them came dead, and one failed after the jumper change.

2nd overclock (with 450mhz cpu):
500mhz (5x100mhz)
Xbench cpu score: 22.3
Note: This sucked. Now really stable, but I didn't get a performance gain like I got with the 400mhz cpu, and Quake 3 still ran like crap.

So here I decided to do the FSB overclock. Knowing I would end up with 4.5 x 133 which would be too fast, i jumpered a cpu to 3.5 multiplier for a 466 clock. This never booted. I put in a 450mhz chip and...

3rd overclock (with 450mhz cpu):
533mhz (4.5x133mhz)
Xbench cpu score: 25.6
Note: That multiply doesn't make sense. It shouldn't be 533. But hey, it worked, stable, and I got a performance gain.

4th overclock (with 450mhz cpu):
533mhz (5x133mhz)
Xbench cpu score: 29.3
Note: Ok, the clock is still not right. This is the same cpu that did the 5x100 so I know the multiplier is set right. But hey, its doing better in the scores!

Conclusion: Success! 533mhz seems to be the top out with the NVRAMRC script in place. But there is a considerable performance gain everywhere (booting, app loading, etc). Most importantly, my Quake 3 now runs very smooth @ 1280x1024 with max graphics settings. I am a very happy camper. I can take pictures of the solder job if anyone requests them. I do recommend this if you have some good technician skills.

eBay shop link for the cpus:
http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=370206261966

Clock guide:
http://power-mac-g4.com/g4clockup.html

FSB guide:
http://www.xlr8yourmac.com/G4ZONE/sawtooth/SawtoothCPUdesign.html



SmurfBoxMasta
May 30, 2009, 07:44 AM
Congrats!

But FYI, been there, done this......years ago, I had my "450" sawtooth up to 600mhz, and 2x 350mhz smurfboxes up to 550, neveranottaproblemo. But my friend across town couldn't get above 550 with his ST though :eek:

this just proves that each individual chip out there has it's own tolerances for o/cking, regardless of what the published specs say :D

Hrududu
May 30, 2009, 10:40 AM
Congrats!

But FYI, been there, done this......years ago, I had my "450" sawtooth up to 600mhz, and 2x 350mhz smurfboxes up to 550, neveranottaproblemo. But my friend across town couldn't get above 550 with his ST though :eek:

this just proves that each individual chip out there has it's own tolerances for o/cking, regardless of what the published specs say :D
How did you get a 350MHz G3 clear up to 550? I've never been able to pull more than 50MHz out of any processor I've tried. Extra cooling?

SmurfBoxMasta
May 31, 2009, 04:09 PM
How did you get a 350MHz G3 clear up to 550? I've never been able to pull more than 50MHz out of any processor I've tried. Extra cooling?

it's De Fans, De fans!

Put 1 on top of the heatsink, 1 in the top of the case, changed the case blower to a higher-cfm unit, and replaced the factory gunk with real Artic Silver thermal paste......

Hrududu
May 31, 2009, 10:45 PM
it's De Fans, De fans!

Put 1 on top of the heatsink, 1 in the top of the case, changed the case blower to a higher-cfm unit, and replaced the factory gunk with real Artic Silver thermal paste......
Thats pretty awesome. I've got a 450MHz processor in one of my B&W's and for some reason it doesn't like running at 500MHz. I've gotten it to boot a few times, but thats about it. Think an extra fan could make that 500MHz pretty stable?

zmttoxics
May 31, 2009, 11:23 PM
Thats pretty awesome. I've got a 450MHz processor in one of my B&W's and for some reason it doesn't like running at 500MHz. I've gotten it to boot a few times, but thats about it. Think an extra fan could make that 500MHz pretty stable?

Some chips just can't be optimized. Adding fans only helps if the chip is unstable because of heat.