i7 increasing automatic voltage

[deagz]

I have a i7-950 and an Asus Sabertooth x58. Naturally when with default "auto" settings, the cpu's voltage scales from 0.9v to 1.2v depending on load and thus cpu speed (speedstep). However when I raise cpu speed via BCLK, the vcore is increased automatically. At 3.6ghz (from 3.06), the motherboard automatically raises max vcore to 1.35 volts. If I set vcore to "manual", the cpu voltage remains constant regardless of load and cpu speed (speedstep still enabled).

I want to be able to manually set max vcore, but maintain the automatic voltage scaling for reduced energy consumption during idle. Is this possible?

 

[Habeed]

That was actually pretty smart of ASUS : 1.35 volts is a very conservative setting that will probably be stable as a rock at 3.6 ghz. The motherboard is actually giving your cpu a little more than it needs for 3.6 probably, but it is very likely to be stable. It's within Intel's specs for safety as well.

Yes to your question. I have your exact same motherboard and the exact same stepping of CPU. Set the CPU voltage mode to "OFFSET" instead.

Here's a setting that will probably work for you : 185 BCLK, OFFSET of ~0.225 volts. (you might need a little bit less voltage but that's what my cpu needs)

DO NOT TRY TO BOOT WITH THE SETTING IT AUTOMATICALLY FILLS IN FOR OFFSET. DUE TO SOME KIND OF BUG IN ASUS's MATH, IT GIVES YOUR CPU WAY TOO MUCH VOLTAGE.

DO NOT SET OFFSET TO MORE THAN 0.3 VOLTS MAXIMUM.

Leave speedstep enabled, can even turn on the C1E power management feature as well. (that is buried in another menu a couple tabs over in the BIOS)

Enable the motherboard fan control, it really quiets things down when you are not under load. Put it on "turbo" and adjust the parameters using the "Fan Xpert" utility that comes with the motherboard.

To test it, so far the harshest program I have found is called "OCCT". An 8 hour stability test using "CPU : Linpack" has proven the hardest for my machine to survive without crashing sometime during the run. I had to do a lot of tweaking to make it stable for 8 hours on OCCT:Linpack, even though it was rock solid on everything else like prime95 and Intel Burn Test. It is stable now, I just finished 30 hours worth of testing.

There's a fair number of other BIOS settings you must set, reply to this thread if you want help.

 

[deagz]

Here's a setting that will probably work for you : 185 BCLK, OFFSET of ~0.225 volts.
DO NOT TRY TO BOOT WITH THE SETTING IT AUTOMATICALLY FILLS IN FOR OFFSET.

I don't quite understand. I see the setting for offset in BIOS, however it does not tell me what the base voltage it is offsetting from. I've tried a low setting, however I cannot seem to get it to boot afterwards, so I stopped trying (flying blind...).

If I am not to boot with the setting, then how do I enable offset? Please clarify. Btw thanks for the help.

 

[Habeed]

The base voltage it is going from is the VID for your particular CPU. This number is specific to your exact chip and was set after testing at the factory.

To find out what the offset does, set it to an offset of 0 and clock it at stock. With a load on the cpu (have prime95 or something running), write down the voltage you see in CPU-z. THAT's your VID (after VDroop, but don't worry about that).

Offset adds a constant to VID. So if you set offset to 0.1, the resultant voltage at load should be about (VID+0.1)

If you want to have 1.30 volts at load, for example, just do 1.3-VID and enter that value into the OFFSET setting. That'll be about right.

Or just pick about 0.2 volts. That's what I did : I kept increasing the voltage until it would boot at 4.2 ghz. I then played with it more, and incrementally increased voltage until it could pass 8 hour OCCT runs at 4.2 ghz. (even one voltage notch less and it would crash during the run).

That turned out to be about +0.23125 volts for offset.

I then clocked it down to 4.1 ghz and set the offset to 0.225 (one notch down) because I want my cpu to last longer. I verified the final settings with 30 hours of OCCT runs.


The offset feature works fine, but it does not appear to be fully developed so it does have a few limitations like you have to do it blind and you can't rely on the number it automatically fills in.

 

[deagz]

I have found why i was getting instability when using vcore offset. "Load Level Calibration" causes my computer to crash when enabled. When set to "Auto", it is enabled when using non stock offset vcore values. Manually disabling Load Level Calibration allows me to uses the vcore offset function.

This will probably be helpful someday to someone who uses the search function.