Q9450 OC Situation

Intel / CUSTOM
February 25, 2009 at 17:18:24
Specs: Windows XP Pro, Q9450/ 4GB
Hi all.

First, here's my specs:

Gigabyte Motherboard, model # EP35C-DS3R(BIOS version F3e)
Intel Core2 Quad, Q9450 processor
ThermalTake Silent 775D CPU Cooler
BFG Nvidia GeForce 9800 GX2 graphics card
Corsair XMS2 RAM (4096-6400, 800MHz, 2 X 2GB)
Cooler Master Full tower HAF Case
Windows XP Pro, SP3

The Q9450 - as I'm sure you already know - is rated at 2.66GHz.

I've been OCing this processor for about two months now at 3.2GHz; I set the CPU Host Frequency to 400Mhz.

I had showed someone a screen shot from the software known as "CPU-Z", and the Core Voltage was getting readings of 1.4V. They said this was a little too high, and that I should adjust it manually. So I went in and changed "Auto" to "Manual", and then adjusted it.

As I'm sure you also already know, the maximum that Intel suggests for the Q9450's VID voltage is 1.36250V.

My motherboard's normal CPU Vcore is 1.25000V, and I tried manually adjusting the voltage to this setting of 1.25000V, but I couldn't boot into Windows. So I kept upping the voltage bit by bit til finally I arrived at 1.32500V.

So for about two months I've been at 3.2GHz and 1.32500V running stable. I've run Prime95 and 3DMark06; it's been stable and good temps.

Then all of the sudden, the other day, my system won't post and I have to go in to the BIOS and make adjustments so I can boot into Windows.

Any ideas as to why my system suddenly wouldn't boot on this overclock I've had for two months? I made no changes to the system in this time.

And is it truly dangerous to leave my motherboard's voltage on "Auto"? Is it putting out too much juice....so much so that it might actually hurt the processor chip?

Thanks for any input or suggestions. I'd sure like to get that 3.2GHz back (or higher if you have suggestions on how to do it!!).

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February 25, 2009 at 17:51:06
"...I have to go in to the BIOS and make adjustments so I can boot into Windows" What adjustments did you make-lowering the cpu voltage ? Whe you switched to manual voltage in the bios, what cpu core voltage was the bios showing ? The cpu-z reading might have been off a little bit. personally, I would never want to exceed the maximum voltage recommended by Intel just for the sake of a couple of tenths of a gigahertz.

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February 25, 2009 at 18:19:34

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February 25, 2009 at 20:13:37
Thanks for the replies.

kx5m2g: When I couldn't boot into Windows, the adjustment I made in the BIOS was to first try upping the volts to the core. Like I mentioned above, I was at 3.2GHz with 1.32500V. So I started bumping this up bit by bit, but then I even hit that number recommended by Intel of NOT going past: 1.36250V. Even at this it still wouldn't boot into Windows.

So instead of pumping more volts, I lowered the FSB and brought the speed down to 3.0GHz, and the volts at 1.33750.

I've got a solid PSU, too; a Corsair 750 Watt with a single 60V rail.

jam: I went to that web link you provided over at OverClockersClub. Dang....they got that Q9450 up to 3.7GHz on 1.360V. But then they also mentioned doing some tweaks to the northbridge and FSB voltages. Is that perhaps what I should try?

In my Gigabyte's BIOS, there's no actual wordage for northbridge. Here; check out this screen shot of my BIOS:

There is the part for FSB OverVoltage Control, but no northbridge. BTW....that's not an actual shot from my BIOS; that's a shot from the users' manual. My Normal CPU Vcore is 1.250V

What do you think?

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