Need some pro help to understand what I'm doing here with voltages and my overclock

[Habeed]

My hardware :
ASUS Sabertooth X58 motherboard
i7 930 CPU
Noctua DH-14 air cooler
mushkin ram at stock settings (1600 mhz 7/8/7/20)

I'm running with these pertinent BIOS settings :
CPU Ratio Setting............ = [21.0]
Xtreme Phase Full Power Mode. = [Enabled]
BCLK Frequency............... = [200]
DRAM Frequency............... = [1603 Mhz]
UCLK Frequency............... = [3609 Mhz]

CPU Voltage Control.......... = [OFFSET]
CPU Voltage.................. = [0.2]

QPI/DRAM Core Voltage........ = [1.30000]

DRAM Bus Voltage............. = [1.65]

Load-Line Calibration........ = [Disabled]
CPU Spread Spectrum.......... = [Disabled]
PCIE Spread Spectrum......... = [Disabled]
C1E Support.................. = [Enabled]
Adjacent Cache Line Prefetch. = [Enabled]
Intel(r) Virtualization Tech. = [Enabled]
CPU TM Function.............. = [Disabled]
Intel(r) HT Technology....... = [Enabled]
Intel(r) SpeedStep(tm) Tech.. = [Enabled]
Intel(r) C-STATE Tech........ = [Enabled]

I'm at 4200 mhz with hyperthreading, the C-STATE power management, and speedstep left on.

My question is this : what the heck does OFFSET voltage do for the CPU core vs. manual? I tried it on manual at first, setting it to 1.35 volts for the CPU. I then toggled it to offset and ASUS's bios wanted an offset voltage of 0.5. Even at stock settings, ASUS wanted something nasty like 0.4. When I booted with that setting, CPU-z said that my core voltage was 1.5-1.6 volts!!! Ouch. So via trial and error, I found that 0.2 somehow comes out to a load voltage of 1.344 (with a spike to 1.36 when you take off the load) and an idle voltage of 1.128.

I don't understand mathematically what this offset setting is actually doing. The stock voltage for a 930 is 1.275 volts, so in theory my actual load voltage should be 1.475 volts. Instead it's 0.1 volts lower. What's going on here?

By the way, this system is "mostly" stable : it survived a few hours of IBT, and some gaming today, but there was a blue screen last night that I have yet to track down. Kinda frustrating, but I guess that's what you get for running your CPU 50% over stock.

 

[Bartman39]

Dont like that "Offset" setting either its sounds very flakey...?


What is your CPU VTT voltage...? You may have to raise it from the normal 1.1 volts to 1.3-1.4 this can stabilize the memory controller so the ram can run properly... Also you may have your ram timings a tad tight so that could also be the cause for the BSOD...? Might loosen them up a bit and do some more testing...

 

[Habeed]

I don't know what VTT is...it's not in my BIOS settings. Everything I didn't list here is set to default.

I gave it a teensy bit more juice...Voltage OFFSET from 0.2 to 0.21875 and so far it's stable. Not 100% certain of that yet, it's survived three hours of stress testing but not an all nighter yet.

I think V OFFSET is the right way to configure the bios. Your CPU voltage is supposed to drop at idle when the CPU cores ask to be under-volted at the lower clocks. OFFSET means that whatever the CPU asks for, my motherboard gives it 0.2 volts more than that, allowing for higher overclocks. With an offset of 0 I can't even boot the machine.

 

[Habeed]

So far so good....

 

[Bartman39]

QPI/DRAM Core Voltage........ = [1.30000]

This is the VTT also so you already have it raised... Sounds also like you may have it stabilized but if not bump it to 1.35 which is ok also... Might allow you to lower your cpu core voltage back a bit...?

Still kinda unsure on that Voffset...? With Speedstep enabled and using C state as well it will throttle the cpu and the voltage and should also work with a manual setting or atleast mine does...? Of course every board maker likes to come up with their own bells and whistles... Nice board BTW, I downloaded your manual to check it out and like the layout and features for sure... ASUS makes some good quality stuff no doubt... Keep posting your results and be sure to run Prime95 to know without a doubt...

 

[Habeed]

Yeah I took a risk on this board. No reviews, and some bad things said about it. It's basically the same as one of the other premium ASUS boards but it comes with a 5 year warranty. It also has a ceramic coating on the heatsinks which makes them feel rough to the touch and they claim they used longer life/heavier duty components on the board itself.

In any case I'm running at 4.2 stable 24/7 it seems, and I was able to boot with 4.4 though it froze immediately upon starting Intel Burn Test.

It does need a fan on the northbridge, which more hardcore O/C boards already come with. But a $3 80mm fan is keeping the northbridge plenty cool.

 

[miahallen]

Hopefully he won't need that much VTT with those lower mem speeds and only dual channel. I'm running an almost identical setup right now and I only need 1.21V VTT....I blogged about the setup here:
http://www.techreaction.net/2010/09...r-saving-features-enabled-its-getting-better/

Habeed, check the guide in my sig if you want another approach

 

[Habeed]

Thanks for the advice.

I'm getting very similar load voltages to yours despite adding +0.20685 volts as my "offset" setting. I am guessing that "Dynamic Vcore" is the same thing.

The reason is that I've got "load line calibration" turned off. Your motherboard knows that there's some voltage lost due to the load and is giving you extra juice to compensate. Dunno which setting is better. Since it seems stable now I'm not going to screw with it unless I get a BSOD.

I've got my QPI/VTT left at the higher voltage of 1.325 volts. However, my northbridge is set to 3600 mhz not 3200 mhz so I need the extra juice. This makes my L3 cache a little faster though it probably makes minimal performance difference. I may try turning this off if I get a BSOD with these settings.

My load temperatures are almost identical to yours. I don't like exceeding 80C but it can't be helped. Interesting, I have the exact same problem : the core on the left in realtemp registers a higher temperature than the other cores. I have a theory that the actual physical layout of the cores on the processor die is not symmetric : the leftmost core may be near something heat producing like the memory controller.

 

[Shmee]

so far very nice. what is your load vcore? You should be safe till 1.45 with better cooling, but it looks like you may be temp limited so far. In other words, VID+.2V (or whatever setting you are using)=?

 

[Habeed]

1.344 to 1.36 according to CPU-z. I know I "should" be safe with more but like a lot of people here I find myself wanting to increase voltage as little as possible to reach stability.

Also, yeah, I'm temp limited : with my ambients (about 74 farenheit) and air cooling (albeit with the best cooler on the market) I can't do much better. I could try another remount of the heatsink (this is my third one, with the best temps) or some lapping to eke out another degree or two. Or I could put noiser fans on the air cooler. Or I could spend $300 on a water cooler (the cheaper ones don't beat a noctua dh-14).

Or a solution I have kicking around in my head : I'm thinking about enclosing my whole computer in something and running a portable air conditioner inside the enclosure. If I could get the temp inside down to 50 farenheit or so, it would give me temps as good as the best water cooling for a lot more convenience. A portable A/C would be cheap, too, bet I could find one for $100 (that's what a new window unit costs)

 

[Shmee]

you should be able to get better temps then, I know when I used my lapped true black with push pull on my 920 @ 4.2, 1.4V, temps were in mid 70's at load. what is your airflow/fan config like?

 

[Shmee]

hmm, with my new setup, the 980x gets around mid 60's with true and only one fan under linx.