Overclocking Intel Q8400 to 3.00ghz

Microsoft Windows xp home edition sp2b
December 12, 2009 at 14:33:00
Specs: Windows XP, P4 2.00ghz
I am having some trouble overclocking my Intel Q8400 cpu to 3.00ghz.

I have a Asus P5Q Pro Turbo motherboard.
700w PSU.
4gb of DDR2 Ram at 1066 PC2-8500.

I have increased the FSB from 333 to about 363. If i go over 363, I my system becomes unstable and crashes.

I have read in some other forums that you have to increase the voltage of the CPU?
Under the BIOS, I see a lot of options that are related to the CPU voltage, but I am unsure of which ones to adjust.

Below are the options for the CPU voltage:

In the BIOS, I have the DRAM Frequency set to AUTO.

CPU Voltage AUTO
CPU GTL Reference AUTO
FSB Terminal Voltage AUTO
NB Voltage AUTO
SB Voltage AUTO

Which options need to be adjusted?? Thanks...

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December 12, 2009 at 14:47:39
You have to run the RAM at the same frequency as the CPU.

Your CPU runs at 1333MHz FSB which is 333MHz frequency. Your RAM runs at 533MHz frequency (1066MHz DDR). When you increase the CPU freq, the RAM freq increases automatically. The RAM is what's holding you back from overclocking successfully. Underclock the RAM to 333MHz (667MHz DDR), THEN overclock the CPU.

Since your board can handle 400MHz frequency (1600MHz FSB), I suggest that's what you shoot for. Clock the CPU at 8 x 400MHz (3.2GHz) & do what you gotta do to get the RAM to run at 400MHz frequency (800MHz DDR). More than likely you will have to change the DRAM setting from Auto to 667MHz.

And don't use the AI Overclock Tuner...set it to manual & select all the settings yourself. Set the PCIe to 100MHz & disable all Spread Spectrum settings.

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December 12, 2009 at 16:12:21
Thanks, it is running stable at 3.2ghz.

Other concern is the CPU voltage.

In Core Temp 0.99.5, its 1.2875 V under VID
In CPU-Z, its 1.336 V under Core Voltage.

Is this a reasonable voltage for this CPU clock speed, or can it be reduced and maintain stabability?
If it can, which settings in the board have to be changed?

My temps are 32C for Core# 0 and 1. 36C for Core#2 and 3. Max temp is about 39C for either core.

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December 12, 2009 at 16:17:03
I don't know what the default voltage is supposed to be. Intel gives a range of 0.85V – 1.3625V, so either way, you're good.


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Related Solutions

December 12, 2009 at 21:07:52
Don't forget to run prime95 to check if overclocked cpu is stable.

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December 14, 2009 at 01:13:12
I ran the prime95 torture test for about 1.5 hrs and no errors where reported. Should I run the test longer??

My average temp during the test was 43C - 45C . Max temp reached was about 48-50C.

My CPU voltage is 1.2875 V -set to auto in the BIOS.

If I increase the FSB from 400 to 425, what would I have to set the DRAM settings to to keep the 1:1 ratio?

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