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I'd like to try a little voltage mod on my CPU, I'd like to know how much further I can push this CPU.

Does anybody now the maximum standard voltage which an i7 720QM or a 920xm uses?

I just looked at some Intel datasheets, and I only found the "absolute maximum rating" for the VCC (core voltage) which is 1.45V. I guess the actual max voltage has to be distinctly lower, but I'm not sure. The VID table goes up to 1.5V.

Some of the old Core Duo had a VCC of about 1.125V at their maximum multi (if my source is correct), and the "absolute maximum rating" was 1.6V (assuming I didn't make a mistake while looking this up)

Without knowing the max voltage the CPU uses it's gonna be hard to do more or less sane mod.

Any information would be appreciated.

Edit: @unclewebb , as far as I remember you don't know a way to manipulate the voltage per software... (and I haven't seen any hint about how to do this in the Intel documents I've read so far), but do you know of a method to read out the core voltage of the first gen i7?

Knowing the state of the 7 VID bits would allow to read out the voltage.

Edited by svl7
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  • Founder

I checked and neither CPU-Z nor TS report any voltage for my CPU not even HWiNFO64, but from within BIOS you have the option to increase it up to 150mV. I have it at +75mV cause otherwise it gets hot really quick

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In case I can't find any table which shows the voltage value for the different multis or a software method to read out the voltage, I'll have to measure the voltage manually. Shouldn't be too hard, I just need access to a VCC pin and to ground.

The problem is, I don't have such an accurate multimeter. Maybe I can borrow one somewhere... the other idea would be to take my system to the students electronic lab at the university, then I could use an oscilloscope... this should work, but it's closed most of the time atm since the term ended already a while ago.

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Indeed when I had my R2 I searched high and low everywhere there just isn't a voltage reading available at all on mobile I7 generation 1. Also my best performance for everyday overclock was derived from +0MV in the range of about 3.59ghz to 3.50ghz... It was amazing at this range on 920xm and I would guess on the 940xm too... Never go too hot on stock volt and it could handle 4 core through those GHz ranges... On shorter benches +75mv was okay before heat got to build and allowed into 3.7ghz range...

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  • 2 weeks later...

Ok, since it seems that there's no method to read out the voltage with software I decided to measure it directly at the CPU.

The datasheet of the CPU describes each pin, there are VCC (processor core power supply) and VSS (processor ground) pins directly at the edge of the socket, which makes it easy to measure the voltage.

VCC_sense and VSS_sense would've been possible as well, but they're not at the edge of the socket, which makes it more difficult to put cables there without accidentally touching another pin and shorting something.

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I was mainly interested at the voltage while the CPU works at the max multi (26x) on all threads. My multimeter always reported 1152mV. There's of course a certain inaccuracy while measuring this, especially since I don't have the most expensive equipment, but it's accurate enough for my needs.

This value will allow me to figure out a VID pinmod for raising the voltage a little bit.

At idle the CPU was at about 900mV. In case you're interested in the voltage at a certain multi, let me know as long as I still have the cables in the socket. Though after reading some Intel datasheets it seems that the voltages may vary from CPU to CPU, I'm not quite sure about this, maybe someone here knows more about this.

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