Intel Speedstep doesn't seem to change the voltage

[the FooL]

I have an old setup:
Asus Striker Extreme (680i SLI) BIOS 2002
E6850 set to 4GHz@400FSBx9

I decided to overclock it in the hopes of getting another year out of it.

I noticed that even if I set all the voltages to Auto, CPU-Z does not show the core voltage changing. Only the multiplier.
I set it to stock and noticed the same thing.

I was under the impression that if I enable E1ST and/or C1E, the voltage would be reduced.

Also, I noticed that when I bumped up FSB, Vcore was bumped up to ~1.45@400 vs. the ~1.35@333
Isn't it supposed to just use the Vid that's in the CPU when Vcore is set to Auto?

Current, I've forced Vcore to be ~1.35 and my system is running stable (so far. Orthos @6 hours). High @57C vs. 62C when Vcore was at ~1.45
Since I noticed a big drop in temp, I'm pretty sure that the voltage was not being dropped during idle.

I've tried looking but I didn't find anyone mentioning how the voltage wasn't changing.
Most people who overclocked just disable Speedstep to begin with.

Thanks.

 

[MJinZ]

Either your CPU/Mobo does not support undervolting, or your Mobo's BIOS disables it when the CPU is overclocked.

 

[the FooL]

Thanks.
I'm assuming the the MB doesn't monkey with voltages if any overclock attempt is done.
So long as the multiplier drops done, I guess I'm saving some wattage and more importantly, heat.

 

[MJinZ]

Thanks.
I'm assuming the the MB doesn't monkey with voltages if any overclock attempt is done.
So long as the multiplier drops done, I guess I'm saving some wattage and more importantly, heat.

Yup, many people disable it anyway as it can occasionally be a source of instability when overclocked.

 

[Voo]

So long as the multiplier drops done, I guess I'm saving some wattage and more importantly, heat.

You do, but it's rather minimal when compared to what a voltage drop could do (dynamic power consumption is 1/2 * C * Vdd^2 * f and static power consumption is Idd * Vdd; or easier to understand: With everything else equal a 10% drop in f results in 3.3% less energy while a 10% drop for Vdd results in 13%). But if your MB doesn't support it, not much you can do about it..

Other than that: I wouldn't be comfortable with 1.35Vcore for a Core2.

 

[formulav8]

My q9450 doesn't change the voltage either using a Gigabyte P35-DS3L based mobo, doesn't matter if the cpu is stock or oced. Not sure why since I have eist, c1e, and really all power saving features including thermal management enabled. Oh well.... Not a huge deal to me I guess.

 

[coffeejunkee]

Because you're using fixed vcore value? If so, eist or c1e won't lower it.

In my experience auto value only reads vid at stock fsb/bclk. And increasing fsb results in fairly liberal overvolting.

What you need is a motherboard with a dynamic vcore setting. It's kinda hard to find out which ones have it and which don't since it's not generally mentioned in reviews. Afaik Asus and Gigabyte P45/P55/X58 mobo's have this option, but I'm not sure about other brands.

 

[NumericalMethods]

Because you're using fixed vcore value? If so, eist or c1e won't lower it.

In my experience auto value only reads vid at stock fsb/bclk. And increasing fsb results in fairly liberal overvolting.

This 100%

 

[the FooL]

You do, but it's rather minimal when compared to what a voltage drop could do (dynamic power consumption is 1/2 * C * Vdd^2 * f and static power consumption is Idd * Vdd; or easier to understand: With everything else equal a 10% drop in f results in 3.3% less energy while a 10% drop for Vdd results in 13%). But if your MB doesn't support it, not much you can do about it..

Other than that: I wouldn't be comfortable with 1.35Vcore for a Core2.

Isn't 1.35Vcore the standard for the C2D E6850?
At least from what gets read of the CPU 1.35 is supposed to be Vid.

 

[MJinZ]

Because you're using fixed vcore value? If so, eist or c1e won't lower it.

In my experience auto value only reads vid at stock fsb/bclk. And increasing fsb results in fairly liberal overvolting.

What you need is a motherboard with a dynamic vcore setting. It's kinda hard to find out which ones have it and which don't since it's not generally mentioned in reviews. Afaik Asus and Gigabyte P45/P55/X58 mobo's have this option, but I'm not sure about other brands.

Not sure what you mean by dynamic VCore.

If Speedstep works properly, then you can set VCore to whatever you want, but at lower multipliers, the Vcore will drop. At load, there are also other settings known as VDroop or less commonly, Load Line Calibration that will affect how much voltage actually gets to the chip during load.

 

[coffeejunkee]

Dynamic vcore: I can specify how much extra (or less) voltage should be added to the vid. So I got 3 settings: auto, fixed and dvid.

Only when I use auto or dvid setting will the voltage drop. If I use fixed vcore it will not drop no matter if eist or c1e is enabled (tested this).

Vdrop/vdroop and llc has nothing to do with this. There's drop/droop with every voltage setting, auto, fixed or dvid.

 

[Voo]

Isn't 1.35Vcore the standard for the C2D E6850?
At least from what gets read of the CPU 1.35 is supposed to be Vid.

Ah yeah, thought those were also 45nm chips, sorry - 1.35 should be fine for a 65nm version.