i5 Voltage and Power Management

[prime2515102]

I have a Gigabyte Z68X-UD3H-B3 with an i5-2500K and a Corsair H100 cooler.

Is it possible to use power management so the CPU clock gets lowered while idle but keep a constant voltage?

I set my voltage to 1.416V (or something like that) but when I load the CPU it jumps to 1.5V and that seems like too much. It's also pretty erratic, moving between 1.46 and 1.5 (these numbers are according to CPU-Z which match Gigabyte's TouchBios utility).

It's stable at 4.8Ghz but I would like to use less voltage.

I have turbo boost disabled.

The CPU power management settings say they change clock speed and voltage, but not one or the other.

Even better would be having the voltage drop too, but not go over what I set it at. Is that possible?

Can't have the best of both worlds?

I'm brand new to i5 overclocking so if more information is needed please let me know.

Thanks

 

[SonDa5]

That should be controllable in your BIOS voltage settings. My guess is that line load calibration settings are effecting your increased voltage under load.

 

[Tsumi]

Yes.

Use offset voltage when overclocking, not manual voltage. This way, you're telling the board what the max voltage levels should be, and it will increase it to that according to load. Basically, something like +300 mV or + 0.3 V or whatever voltage setting you would need.

If you leave things like EIST and C1E enabled, the i5 2500k will automatically downclock to 1600 mhz at idle, and will similarly lower voltage when you have offset voltage enabled.

LLC can make your voltage go over like that, and chances are, if you tried putting in a lower voltage and failed the overclock, you need that much voltage.

 

[prime2515102]

ahh ok, I'll play around with that, thanks

 

[prime2515102]

Well that did the trick. I had to set it a bit higher than I was hoping but it seems good. It's giving brief peaks of 1.44V but I'm ok with that. The numbers in the CMOS don't seem to line up with the results and I haven't quite picked up on the pattern yet.

I still need to do long term testing but it's stable so far.

Here are my results running Lynx (stock fans on H100 set to low, realtemp is uncalibrated, just opened for before/after comparison). Anybody know how accurate those numbers in Lynx are? 119GFLOPS seems crazy...

 

[prime2515102]

P.S. That's called 'Dynamic VCORE' in my CMOS. I don't know why I didn't notice it before.

I had to set it to +0.160 and it's setting VCORE to 1.355 (had to set it to normal to open the dynamic VCORE setting).

 

[Tsumi]

Fluctuations are normal. Some boards are better at controlling the fluctuations under load than other boards are. Gigabyte has been one of the more unstable ones, but not grossly so, based on [H] reviews. I think Asus has the best voltage fluctuation management, followed by MSI, then Gigabyte. Not sure where others like Biostar stand. It also depends on the specific board being tested.

 

[Russ]

119 is fine for a 2GB test. That's right around what I get with my 2500k @ 4.8.

Flops go up if you test with more RAM.

I've got the same board too. Good that you have the voltage set up like that, but IMO it doesn't really matter too much if you use a voltage offset or if you set it statically. At idle it doesn't hurt you to have a higher voltage, there's not much running through the chip at those settings.

I'm currently using:
vcore 1.41 (~1.37v load)
LLC level 4
PLL 1.7

And it's fairly stable. I got a 0x101 after over an hour of LinX with 14+GB used, so I'm thinking that I'll probably use 1.415 or 1.42 vcore later tonight when I have a chance to do more stress testing. 4.8 is my 24/7 speed.

Btw CPU-Z shows an idle voltage of 1.428 or something, even with 1.410 set in the BIOS.