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I have a brand new computer (built yesterday) with an AMD Phenom II X4 965 on an ASUS M4A89GTD Pro motherboard. Today I noticed heavy vCore fluctuations: between 0.90V (idle) and ~1.30V (load). CPU-Z shows how my core multiplier goes from 4x (idle) to 17x (load). After doing some research, I discovered that the default Windows 7 "balanced" power plan sets the "Minimum processor state" setting to 5% by default. Having changed it to 100%, my multiplier now remains at a constant 17x, and my vCore appears to have stabilized around 1.27V.

My system temperatures are pretty good, with the processor idling at around 30°C, reaching ~45°C when playing demanding games.

My question is this: is there any reason to worry about these vCore fluctuations, seeing as they are apparently very closely tied to the operating system's management of the CPU core multiplier?

Edit: could it be Cool'n'Quiet working in the background? If so, are the multiplier and vCore differences normal?

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up vote 2 down vote accepted

This is all completely normal. When you are idle, you don't need your CPU running full-tilt. The drop in vCore matches the drop in the multiplier, because the extra juice is not needed by the CPU. There isn't much reason to change this behavior unless you are overclocking, because it will save you on your energy bill (slightly) and keep ambient temps down while extending the life of your components.

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Thanks -- I wish I knew more about hardware, as little things like this sometimes make me freak out a bit. :) – Martin Törnwall Oct 14 '10 at 20:25

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