Gigabyte P34G Undervolting Guide (Intel Haswell)

I didn't see any other concise step by step written guide like this, so I thought I'd make one.

It's pretty simple and shouldn't be hard to do - just be careful not to accidentally overvolt or undervolt too much without testing. Use at your own risk.

This reduces the power consumption/heat slightly at idle - but has a much bigger effect when under load.

What I have is a Haswell i7-4700HQ processor, though it should apply to many other similar procs in similar laptop systems.

Basically you can use the Intel XTU (Intel® Extreme Tuning) Utility to undervolt your processor

Steps:

1. Get the tool here: Intel® Extreme Tuning Utility (Intel® XTU) (Though it says Desktop motherboards, I have used this specific utility myself and it works).

2. Then select Manual Tuning and (after accepting the terms) set the Dynamic CPU Voltage Offset to -90mV or so.

3. Run the Stress Test (at least 15 minutes recommended).

4. If the Stress Test passes, do some other testing as you feel appropriate. If you have a crash or blue screen or other artifacts, then reduce the undervolt by 10mV or so and then retest. If the computer stays stable on both battery and AC with that setting, then congratulations you have found a good undervolt for your system .

Here are the results I've seen from my 15 minute stress test runs in the program (I ran both tests twice to confirm):

Stock Voltage:


With 90mV Undervolt


Note the ~6W lower max CPU package power consumption and ~6*C lower max temperature. Not bad

I have heard of others being able to do 100 mV or more - it may be that I am running the system at full High Performance with Auto Fan and therefore more power is needed (Stealth mode appears to slow things down to keep noise low). But you can see if the Stress Test fails (mine will Blue Screen at -100mV for example) and if it does, when your computer restarts all the settings will be default and you can start over with a lower mV level until you find a stable level.

If anyone has any suggestions on what other settings (such as Core Voltage, Processor Cache Voltage Offset, Processor Graphics Voltage Offest, etc...) that can be reduced in tandem with this to allow for even better results, please let me know and I'll add that to the guide.

I am not responsible for any damage from this, but I have had success reducing power usage, heat and noise and increasing battery life while not compromising performance and probably increasing component lifespan so hopefully it will help others as well.

Hopefully this is useful to someone, if so, if you can reply and me know that'd be great.

All the best,
Peter

 

Hi,

I tested your guide to see if I can squeeze out more battery life and lower the tempeatures a bit.
My settings were: Fan Auto, Performace mode
Undervolting: -100mV Dynamic CPU Voltage offset -> stable, core power consumption: 24W max., 78°C max core temperature (before 82°C)



Haven't yet tried undervoltung GPU or cache, but I'm pretty pleased with my results.

 

Thanks for replying Metatron, glad to hear it helped . I saw my comp telling me I had 5 hours 15 minutes left on battery the other day while using wifi, bluetooth, and fairly high brightness while at 90% - Impossible of course, I think it got it wrong, or was assuming I would run with lid closed . In reality though, I have seen a boost to my battery life - but it is a more modest amount (maybe 20-30 minutes) - I haven't run any sort of scientific test to see for sure though.

Currently while typing this on high performance, wifi+bluetooth active, 90% brightness, fan on stealth and nVidia turbo boost off it's showing 89% battery with 3 hours 7 minutes remaining - that seems reasonable - so roughly ~205 minutes usable battery life in this mode (and using my -90mV undervolt which I have had active all the time, both on battery, and not for 10+ days now).

Note that any GPU undervolt you do through this app will only affect the Intel Integrated GPU and not the nVidia dedicated one - I'd be curious to look into undervolting that one too, but mostly to reduce heat - though there are times I've gamed a little on battery so it could help there too. The other undervolts could help even more too.

Thanks,
Peter

P.S. And, unlike before, my computer has been completely silent this whole time on battery replying to forum posts - really, really like the new 305 BIOS

 

One question remains for me though. If I undervolt using Intel XTU utility, will it keep the settings, even when I close the application and will it retain the settings after a reboot?

If thats not the case I will have to unlock my BIOS again and permenantly undervolt the CPU, but I'm hesitating because its always a risk to flash the BIOS and right now I'm quite happy with my P34G

 

As far as I know - yes, it will .

If you want to check, either find another app that can read the setting or else with the XTU app open do a stress test with some other program (such as 3DMark for example), record the max temp, power usage data, etc.., restart and then do the same test without opening the XTU application and see if there is a difference.

As far as I see though, it does stick between restarts and when I did get a BSOD from doing it too far, the XTU application came up on the next boot with everything reset, so it's been quite safe for me (especially now that I've found the safe level for my proc).

If you did unlock though, I'd definitely use an unlocked 305 - so much better

Peter

 

Thanks for the guide. My results so far:

-100mV passed XTU Stress Test (though it doesn't heat up CPU as much as gaming), seemed stable for office stuff. Decided to play Bioshock (used to hit 99C max on CPU on stock voltage) with a ton of Mozilla tabs opened - it freezed after a few minutes. At -90mV after a few minutes of play, Mozilla crashed Thinking that was due to the undervolt, lowered (or upped ) to -80mV.
For now system seems quite stable. CPU hits 98C max during long gaming sessions.

Maybe wil try -90 and -100 again later, because 98C is still a bit too high.

 

98°C seems a bit too much for me. My CPU heated up to max. 82°C without undervolting at maximum load, the GPU went over 90°C, but i can't remeber the exact temperature. i don't think that those temperatures are normal and they won't benefit the CPU lifetime. The Tj_max (max. temperature, then throttling is applied) for this CPU is 100°C. Did you modify the Laptop or is this the stock configuration?

 

It's basically stock, just swapped the ssd. Well, 15 min XTU Stress test heated my CPU to 91C max, and with -100mV undervolt it was 83C. Room temperature was around 28C. >1 hour of playing Bioshock seems more stressful for the CPU.
At the same time, never seen more than 85C on the GPU during Bioshock (didn't try Furmark or other burning stuff though).

Any advice (other than repasting) on lowering CPU temps is much appreciated.

 

I recommend not under volting your CPU with haswell.

The CPU itself under volts itself when idle, when in load it overclocks itself automatically (which requires more volts) and if it doesn't get enough "juice" it will black out and shutdown.

 

Thats not true. The CPU doesn't "undervolt" itself, it adjusts its core voltage based on its load and current frequency. Undervolting means lowering the CPU voltage by a constant amount (say 100mV) all the time (on top of the CPUs own voltage adjustment). If you do it correctly there are no downsides to this, you do not damage anything. The only thing that can happen to you are instabilities and to get rid of them just reduce the undervolt a bit and you end up with a quieter system with lower power consumption and better battery life. I'm running -100mV without any problem at all!

 

Exactly, agree totally, and as long as when you are stress testing you simulate the maximum load you think you will reach with the laptop (and then some) you should be safe. The one time I remember someone having issues was when he did a 150mV reduction because he only ever tested the system while it was on power saving with CPU restricted to 50% - then when he increased it the system became unstable. But even in that case, after reboot he was able to open up the application and change the value to 100mV and was stable there.

If you plan to overclock then make sure to test what undervolt is stable with everything at the maximum you plan to use. If you do so, you should be safe with the undervolt and your system should be quieter, cooler, with slightly better battery life and generally just better imho. Even the lifespan of components should be better - as far as I can see this sort of software undervolt is completely safe*

By the way has anyone tried undervolting other things than just the Dynamic CPU Voltage Offset?

Peter

(though I am not responsible if I'm wrong and someone please correct me if so)

 

Here are my settings/specs:



everything was tested with Performance/Auto Fan:
0,978V (default): ~28.5W, ~76°C after 10mins
-95mV, ~24.5W, ~70°C after 10mins
So about 4W and 6°C decrease @-95mV. Nice.

Only thing i ran into was undervolting while on battery, XTU jumped over the 1,3GHz limit (default limit when on battery) and pushed all 4 Cores to 3,2GHz while not plugged in. Had to decrease Processor-usage (CPU top perfomance) in energyoptions (65% = ~1,5GHz in balanced mode). Then after 2 reboots everything went back to normal (1.3GHz limit activated itself) and i had to reset all poweroptions. Somebody noticed that too?

Also can somebody tell me how i tell Windows (8.1) to switch form Performance to Balanced when i unplug the notebook (and back to perf when i plug it in).