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OS X panics when OC is above 3.05 GHz


PookyMacMan
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Hey all. :)

 

I've just gotten my CPU temperature stable, and thus have decided to push my 2.4 GHz Core 2 Quad Q6600 a little bit. ;) Right now I'm OC'ed at 3.05 GHz with a 40º C idle temp. I experimented with bumping it to both 3.15 GHz and 3.2 GHz; in Windows it is fine, and the temperature stays (about) the same. In OS X, I get something like this (KP):

Machine check at 0x[somehexnumber] 0x[anotherhexnumber] 0x[yetanotherhexnumber]

and then of course the address locations.

 

I have fixed my DSDT to allow usage of AppleIntelCPUPowerManagement (via HPET and LPC patches); I don't see AICPUPM listed in the backtrace, but could that cause problems? Do you have any other suggestions?

 

I'll post a pic when I get the chance.

 

Thanks,

 

Pooky

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Try to lower the OC with mhz to mhz... i had the same problem... I could OC my CPU to 3.2 without problem, but because of OSX, I had to OC it 3,14 or something like that.

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OK, I'll see what OS X will take. :)

 

I'm also going to try and see if there's anything I can tweak to make OS X happier...maybe inch it up a MHz at a time? Was that what you were suggesting?

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Good idea, I hadn't thought of that; I always let my mobo handle voltage.

 

What did you set your voltage on?

 

BTW, 3.1 GHz works with no problems...

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I'm actually thinking it's RAM over clocking at this point...because I had the CPU Multiplier on x8, and the FSB at 390 (so 3.12 GHz), and that was the max. As I type I am running the machine at 3.33 GHz, with the CPU multiplier on x9 and the FSB on 370. RAM right now is at 1110 MHz. :)

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Good idea, I hadn't thought of that; I always let my mobo handle voltage.

 

What did you set your voltage on?

 

I don't let the mobo handle voltages. I found it tends to use too much in order to make a stable overclock. And voltage = heat.

 

These are my settings (I'm using a Gigabyte board too, GA-965P-S3).

 

CPU Clock Ratio 8

CPU Host Clock Control Enabled

CPU Host Frequency 400

System Memory Multiplier 2.00

FSB OverVoltage Control +0.1V

(G)MCH OverVoltage Control +0.1V

CPU Voltage Control 1.29375V

 

I didn't bother overclocking the RAM.

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I didn't bother overclocking the RAM.

The weird part is that it was over clocked automatically. I didn't do a thing to it.

 

And, it appears that it's not RAM either...but I'm at a stable OC of 3.42 GHz, which is quite good for air cooling. :) I'll try those voltage settings sometime and see if that helps increase stability even more.

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  • 2 months later...

I think thats about all your gonna get on air with your Q6600. When I had mine, for everyday, all season use, 3.2 seemed to be the sweet spot. Ram may overclock too simply because your increasing you baseclock to where even with the lowest ram multi available, it's still overclocked. Even with my i7-920 which is C0/C1 stepping so not as good an overclocker as D0, 3.8 is the sweet spot during Summer, as anything over that I have to start increasing voltage exponentially and above 4.0 would have to take out half my RAM to be stable. Heat's never really a problem with water cooling, but too much voltage scares me. I'm quite impressed with where you already got to, especially if it's stable that way. 3.4 is usually where they start getting a bit flakey

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Yeah, voltage freaks me out too. :| I've never personally adjusted it manually.

 

3.42 is quite stable, runs at about 45-50 C on idle, goes to about 78 on 100% load. And that's on Mac OS; in Win it stays around 37 on idle at in the 50s on full load. ;) When I thought there were stability issues at one point I set everything back at standard clocks for about a month and nothing changed. :P So other than that one glitch (that I found out later was a software compatibility bug), everything works A-OK.

 

CPU: 3.42 GHz

RAM: 1140 MHz

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