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CPU Voltage Settings (Core i7 970 / gigabyte UD3R)

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Mar 25, 2011
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So, any advice on voltage adjustments for my i7 970? I've pretty much got most of this overclocking thing down already, but the voltage settings are still throwing me off.

So far, I've gotten things up to 4.3GHz with a BCLK of 189 (23x CPU) without too many problems, but the only voltage settings I've been changing are QPI/Vtt and the DRAM settings, while leaving the rest on auto. I'm pretty sure I may have overlooked something. Other items, such as the Vcore, CPU PLL and IOH core, I've been leaving untouched at the auto setting with their default values.

Here's what I have so far:

- CPU Core Features -

Turbo [disabled]
CPU Cores enabled [all]
CPU Multithreading [enabled]
CPU halt C1E [disabled]
C3/C6/C7 State [disabled]
CPU Thermal [disabled]
CPU EIST [disabled]
ProcHot [disabled]

- Frequency settings -

CPU Clock [23x]
CPU Freq 4.34GHz (189x23Z)
QPI Clock [36x]
QPI Link 6.80GHz
Uncore Clock [x12]
Uncore Freq 2.268GHz

BCLK 189MHz
Memory [8.0x]
Mem Freq 1.512GHz
PCI Exp Freq [auto]

CPU Clock Drive [800mv]
PCIe clock drive [900mv]
CPU clock skew [ 0ps]
IOH clock skew [ 0ps]


- MB voltage Control -

>>> CPU
Load-Line Calibration [standard]
CPU Vcore 1.22500v [auto]
DVID +0.00000v [auto]
QPI/Vtt 1.17500v [1.25500v]
CPU PLL 1.80000v [auto]
>>> MCH/ICH
PCIE 1.50000v [auto]
QPI PLL 1.10000v [auto]
IOH Core 1.10000v [auto]
ICH I/O 1.50000v [auto]
ICH Core 1.10000v [auto]
>>>DRAM
DRAM 1.50000v [1.62000v]
Term 0.75000v [0.81000v]
Data Vref 0.75000v [0.81000v]
Addr Vref 0.75000v [0.81000v]


It's been confusing trying to look for reliable info on the web because its either specific to certain processessor/motherboard combos, or so general that some settings either don't apply to my setup, or they would be too excessive for a 32nm chip in some areas.

There's also this one rule where one setting has to be within .5v of another, or else you might fry the CPU. (QPI/Vtt and DRAM?)

Anyway, I could certainly use some advice on this, so I can move past the 4.3GHz barrier I'm currently facing. Given that I'm only at about 67°C under full load at this speed, I definitely have some room to work with yet.

Back when I was briefly running the system at 4.5GHz, I was just letting the motherboard handle this stuff by itself by having everything on auto, but it wasn't exactly reliable under a full load. Now that I know better, I'd prefer to know exactly what's going on under the hood so i don't end up with a dead system... :p
 
Ok, so I decided to try approaching this problem from the opposite direction, by setting everything to auto and simply watching what the bios does on it's own. (After all, if it managed 4.5GHz before, it should still work now...)

What I'm learning, is that none of the settings posted above really even make sense short of maybe the DRAM settings.

For example, there's this huge ruckus that you shouldn't exceed 1.25v on Vcore, but left to auto, the bios reports Vcore up around 1.3600-1.3800v and DRAM at 1.5600v, just for 4GHz (175x23). Which seems to go against the grain of most of these introduction to overclocking articles/videos etc...

As for QPI/Vtt settings, there's no way to figure out the current setting the bios is using for "auto" via the bios itself, or in any mac os based utility I can find. Unfortunately, I'm not running a dual boot setup, or I could use something like CPU-Z... (CPU X by netkas is worthless, btw...)

So I pretty much have only the advice of those around me to work from here. :confused:
 
Bones3D,
Looks like you're making good progress with your OC efforts. I was in a similar situation and basically needed to find a good procedure to maximize my OC while controlling all the variables. I had good luck using this site as a reference. http://www.overclock.net/intel-cpus/538439-guide-overclocking-core-i7-920-930-a.html. It didn't apply to my processor specifically (930) but the OC procedures are rock solid and are relevant to 45nm or 32NM.

All the settings you have look good. I do have a couple thoughts.
Odd number BCLK and CPU multipliers are often the best. Stick to those. :)
LLC I have set to level 1 which allows me to control the CPU VCore more directly. I don't like using the auto CPU Vcore as it can cause it to run hot under load. If you're at 67C under prime95(windows) or CPUTest(OSX) then i might not push it much further without refining the CPU Vcore. I would move the LLC to L1 then set the CPU Vcore to 1.28, post to bios, look at the temps and if they look good allow it to boot into OSX followed by CPUTest/temp monitoring. If it's stable then work the CPU Vcore down in steps until the machine isn't stable. You should get better temperatures from there. Once you have that down then i would move the BLCK up in smaller increments until it becomes unstable. Once unstable adjust the VCore to attain stability while watching temps. This will also allow you to bring your ram speed up so that you're not stuck at suboptimal ram settings. (Assuming you have at least 1600MHZ DDr3)

Lastly the CPUPLL on my machine had to be set at 1.88 volts to attain stability. I've read that the Gigabyte Mobo needs a little more juice to the PLL settings when pushing the CPU. If you're stable at 1.8V then i might not touch it.

What tests are you using to check for stability?

Good Luck!

Bones3D said:
... the voltage settings are still throwing me off.

Load-Line Calibration [standard]
CPU Vcore 1.22500v [auto]
DVID +0.00000v [auto]
QPI/Vtt 1.17500v [1.25500v]
CPU PLL 1.80000v [auto]
DRAM 1.50000v [1.62000v]

There's also this one rule where one setting has to be within .5v of another, or else you might fry the CPU. (QPI/Vtt and DRAM?)
Given that I'm only at about 67°C under full load at this speed, I definitely have some room to work with yet.
 
Thanks for the advice, colonel. I think I'm finally getting it after watching over the BIOS's automatic settings changes with my CPU multiplier/bclk entries.

I think one issue I was having was a mix-up in the limits of the core and uncore voltages. Had i kept going blindly, I might well have pushed the uncore up to 1.4v or higher, where it should have been the core value. (I have a method of determining CPU performance dropoff vs Memory/uncore performance dropoff). One of my earlier overclocks had the uncore and ram voltages significantly higher than vcore, that resulted in a one of my cpu cores suddenly going inactive under a full load, followed by the OS suddenly going black. Fortunately, I was watching as it happened and may have prevented damage to the CPU by immediately cutting off the power. (The DRAM and Uncore were within .5v of each other...)

As for how I'm testing everything...

I'm using Temperature Monitor in concert with Apple's Activity Monitor utility to observe the state of each core during testing of every overclock, so I know what is going on just before Mac OS X kernel panics or freezes, and I shift the BIOS settings accordingly. I primarily use Prime95 in torture test mode to observe each overclock configuration under a full load. Any overclock that doesn't crash or freeze the OS, or push temperatures above 85°C, I then send the overclock to Memtest86+ for a minimum of two passes. Any overclock that gets that far is then added to the list of CMOS presets as a known stable configuration until something faster is achieved.

Also, I found a practical use for Geekbench (aside from having it spew out arbitrary values for bragging rights) that helps determine whether you need to increase the uncore and DRAM voltages to move onto the next overclocking value. Geekbench will sometimes report memory performance at 40% less below the usual average when memory voltages become too low to maintain it's stability. Aside from this bit of info, the only other way I've seen to determine this, is to time the overall response time of the OS, such as how quick it boots or launches an app. (but even a poor vcore voltage could result in odd slowdowns, the geekbench test only adds a few number values to help determine what item is causing the slowdown...)

With any luck, I'll determine a maximum potential overclock for my setup in the next few days, though I suspect the max daily use speed will be 4.25-4.3GHz. (Anything more would be showing off needlessly.)

While I'd love to see 5GHz even for a few minutes, it's looking like 4.6-4.75GHz may be the upper limit for this setup without getting careless and experimenting with load-line calibration. (There's a fantastic article somewhere I was reading a few days ago that explains why vdroop/voffset are necessary to prevent damage to the CPU. It can create massive voltage spikes, despite the cooling advantages it may offer.) I also don't plan to upgrade to a cooling system that requires connection to my household plumbing or liquid nitrogen... :p
 
This might be of some use to others out there who are trying to overclock their core i7 units. It's a map of the components that uses terminology similar to that in the BIOS:

corei7map.jpg
 
No problem! Actually, aside from the actual hardware build, this was one of the simplest hacintosh builds I've done. My earlier ones were all commercial machines with wildly random specs. A setup where you control the specs directly is far easier to setup.

Of course, none of this would be possible without the help of Multibeast, iBoot and the community here.

As for how I've been constructing this info, has been to go through much of the same info you enountered, then experimenting in very small increments, adjusting the settings and watching the results relative to on another. Though, I've had to gain a bit of a spine in the process and learn not to get nervous when my system suddenly freezes, shuts down, or fails to boot. The CPU is pretty resiliant, so long as you work small and act quickly, and observe as much info as you can.

As for my progress, I have a solid 4.3GHz that's pretty reliable even with prime95 and memtest86+ sessions. Though, there's about 3 variations on this with the BCLK settings. (my board tops out around 220MHz...)

At any rate, feel free to drop me a note if you have a question about something you're unsure about. Now that I've been work on this a while, I have a pretty good idea of what to expect from different things. Heck, I might even ask you questions given some of the similarities between our systems. (It's always good to network.)

I look forward to seeing how your overclocking attempts turn out.
 
btw... you have a pretty good looking setup. Mine is a bit more subtle, like the Powerbook from the late 90's.

frankpro.jpg
 
I know this is a very old thread ... but I'm trying to max out my i7-970/UD3R, which is currently at 4.0GHz.

It's set at 166x24 @ 1.40v ... and "idling" at around 60ºC ... (Goes up to about 70-75º with Prime95)
But when I try to push it to 166x25 it just reboots and reverts. I'm guessing there are other things I need to tweak.

Can anyone with this setup offer some tips?

My BIOS settings can be seen here:
https://photos.app.goo.gl/10sL7N37mlAIqsrl1

Thanks!
 
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