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Yet another 2500k OC question - Page 3

post #21 of 25
Here's an interesting comparison. The first picture has my Core i5-3570K with a fixed voltage of 1.280 volts and it is using the Windows High Performance power profile with the Minimum and Maximum processor state set to 100%. At idle it is consuming 49 Watts from the wall.

4500mhz49w.png

The next picture is using an offset voltage of +0.060 Volts in the bios. I switched to the Windows Balanced power profile so the CPU could idle down to 1600 MHz. Power consumption is now at 47 Watts instead of 49 Watts so castrating my CPU down to 1600 MHz has saved me a grand total of 2 Watts.

1600mhz47w.png

A core voltage drop of more than 0.500 volts at idle doesn't save you very much. If you look closer, the core temperatures are identical. That leads me to believe that the power going to the CPU in both instances is virtually identical. The extra 2 Watts is likely going to the voltage regulator on the motherboard or something like that.

If you are using the low power C6 state, the core voltage that monitoring software shows you becomes meaningless at idle. High or low voltage or high or low multipliers in CPU-Z don't make much of a difference at all. Definitely not worth losing any sleep over.

For maximum stability when overclocking, I prefer a fixed voltage. Doing this allows you to come up with a stable overclock very quickly without needing to do a pile of testing.
post #22 of 25
How come that first Realtemp shot shows the CPU at 36 instead of 45? Looks like it is still throttling down.

And is it really "castrating" the CPU by idling at 1600 if it speeds back up under load?
Edited by Forceman - 5/11/13 at 3:21pm
post #23 of 25
Downclock to 1.6 ? wait you mean like Intel Speedstep option in BIOS? blinksmiley.gif
post #24 of 25
Quote:
Originally Posted by Forceman View Post

Offset will allow the voltage to go down at idle, but it won't have any effect on the clock speed. Even with a fixed voltage you can still downclock at idle.

I use offset currently and my CPU downclocks fine so a bit confused.

Just wondering if there's any reason to downclock if you're using set vcore. I thought it would pump the same voltage no matter what.

Usually disable all the speedstep stuff when using set vcore. The CPU can downclock, but why run 1.6ghz at 1.3v when you can do 4.x at the same voltage?
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Main Rig
(17 items)
 
*Not so* Main Rig
(13 items)
 
 
CPUMotherboardGraphicsRAM
I7-2600k Asus Maximus Gene-Z Zotac 970 32 gig (4x8gig) Cosair Dominator 1866 CL9 
Hard DriveHard DriveHard DriveOptical Drive
Samsung 830 - 128 gig VelociRaptor 300gig Random Toshiba 3TB Liteon 24x DVD-RW OEM  
CoolingOSMonitorKeyboard
Cosair H100 Windows 7 Pro x64 Xstar 1440p Realforce TKL 
PowerCaseMouseAudio
Seasonic x750 Arc Mini RAT7 Fiio E10 
CPUMotherboardGraphicsRAM
Phenom x4 955 BE Gigabyte 870a-UD3 XFX 6870 4 gig G-skills 1600 mhz CL9 
Hard DriveOptical DriveOSMonitor
64 gig Microcenter SSD / 1TB Samsung F3 Random DVD-RW W7 64 Bit Ultimate Asus VH236H 
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post #25 of 25
Quote:
Originally Posted by Forceman View Post

How come that first Realtemp shot shows the CPU at 36 instead of 45?

When any of the low power C States like C1E, C3 or C6 are enabled, the multiplier of the CPU will be constantly changing internally as cores enter and exit these C States. That is what RealTemp is reporting. I guess this means that cores do not enter and exit the C States at a steady 45 multiplier.

What I was trying to show is that using the Windows Balanced profile to lock your idle CPU at 1600 MHz and dropping the core voltage over 0.500 volts does not result in any significant power savings when you are using the C6 low power C State.

The retail Ivy Bridge CPUs are capable of running at 800 MHz but this feature is not used by Windows. Probably because there is no benefit to running a CPU this slow.

ivy800mhz.png
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