cpu offset voltage question.

Armadillo · 22 Jan 2012 at 19:20

Just a quick question about the offset cpu voltage. I know it's + or - default, that is when the cpu is running it's normal speed and voltage?

My x4 955 is 1.380v under load and shows 1.380v in bios, but when it clocks down to 800mhz it drops to 1.1 or so.

So if I want to use the offset voltage to get 1.42 so I can go to 3.8, I have to set the offset to + 0.04? Then it should go to that under load and drop when not. As manual mode just keeps it at 1.4 all the time.

Board is a sabertooth 990fx.

Thanks

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pgi947 · 22 Jan 2012 at 22:33

Not sure how it works with AMD chips/boards so apologies in advance if anything is wrong.

Usually you're offset is taken from the VID (coretemp). +/- from this to hit the desired voltage.

So if the VID shows 1.38v, and you want 1.42v then +0.040 would be right. When idling (presuming using AMD's version of speedstep to reduce core speed and voltage) the offset will add 0.040 to the default idle voltage too.

j.col · 23 Jan 2012 at 19:55

pgi947 said:
Not sure how it works with AMD chips/boards so apologies in advance if anything is wrong.

same here.

What i do as every cpu is slightly different.
i just raise the voltage a couple of levels. then stress test, if it fails i will raise it 1 level and retest, if it passes, thats the voltage i need.

Armadillo · 24 Jan 2012 at 03:44

Seems correct. Been playing with it tonight and it adds the offset to both idle and load voltages. Bit of trial and error to get voltage I want though. With manual setting going 1.42 keeps it exactly there or near enough.

With the offset though, adding 0.04 or near enough (goes up in increments), had it at 1.42 in bios and clocked up but not under load, and at 1.52 underload from linx. I guess that's because it's just added on top of default as I think I've seen the default settings go to 1.41 or so under heavy load. 1.380 is just what it shows in bios and when it's at 3.2, but not really under load.

Gave it a nudge down a setting, so 1.44 under load from linx. Seems to be initially stable at this setting though. Went through a 20 run of linx with problem size at 20K with no errors (settings I got from another thread) and max temp of 55C

, got some overhead as well as cpu fan was only at 1400rpm, can go to 1800.

Will have to get a topic started on stablity testing, make sure it's 100% and see how low I can get the voltage or how high I can get speed.

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Thanks for the help.