The "Undervolting" Guide

[unclewebb]

I can't think of any reason why it should be. I deliberately programmed it so even when logging, the log file is only written to the hard drive once per minute. When not logging, ThrottleStop shouldn't be writing anything to the hard drive.

I'll definitely look into this because I hate software that accesses the hard drive when it doesn't need to. Are you using TS to monitor GPU temps?

Edit: I have an ATI GPU. When ThrottleStop is monitoring GPU temps, there is a pile of hard drive activity. As soon as I disable that, there is zero hard drive activity. I guess you'll have to complain to ATI since I'm asking their driver for the GPU temperature. Typical ATI code bloat.

If ThrottleStop has the Log File option checked then you will see the once per minute log file writing as I mentioned before. There will also be some hard drive activity when the program first starts as it reads the settings as well as when TS exits but that's all the hard drive activity that I could find. I was pleasantly surprised actually, except for the crappy GPU code but that didn't really surprise me. Other than for testing purposes, probably better turning that crap off. Let me know what you figure out. I'm more anal than most when it comes to disk thrashing and avoid it as much as possible.

Edit2: ThrottleStop by itself doesn't touch the registry. I hate that thing. Asking the ATI driver what temperature the GPU is at results in 400+ accesses to the registry every time the temperature is updated about once every 5 seconds. Pretty pathetic.

[TigTex]

I don't have GPU temperature monitoring on neither logging... And I also have a nvidia gpu.

I use throttlestop with "set multiplier" "power saver" "slfm" "bd prochot" on, minimized to taskbar.

[unclewebb]

My laptop has an Nvidia GPU but for this test I have GPU temperature monitoring turned off. This is with ThrottleStop open.



After 10 minutes and about 100,000 events, not a single event was caused by ThrottleStop. Nvidia GPU temperature monitoring will cause regular access to the registry. Once again, I'm just asking the Nvidia code for the GPU temperature. When GPU monitoring is disabled in ThrottleStop, there shouldn't be anything showing up in Process Monitor other than when ThrottleStop starts up, ThrottleStop exits or if you open up ThrottleStop after it has been minimized to the system tray. After it has opened up, there is no access to the hard drive going on that I can see.

Can you tell me how you have Process Monitor setup. Am I missing something? I've tried to duplicate your settings but I'm not seeing any disk activity. I've tried this on my desktop which has an ATI card and on my laptop with an Nvidia GPU.

Here's the version I'm using.

ThrottleStop 2.00 Build 26
http://www.fileden.com/files/2008/3/...rottleStop.zip

[e2zippo]

unclewebb: looks lite a neat little program you've made but how exactly do I use it, any basic guidelines, I suppose I have to check "clock modulation, chipset clock mod and multiplier and then set my voltage ID, but what settings do I use?

I'm a bit of a noob once again since the last time i undervolted was quite some time ago

[TigTex]

Can you tell me how you have Process Monitor setup. Am I missing something? I've tried to duplicate your settings but I'm not seeing any disk activity. I've tried this on my desktop which has an ATI card and on my laptop with an Nvidia GPU.

Here's the version I'm using.

ThrottleStop 2.00 Build 26
http://www.fileden.com/files/2008/3/...rottleStop.zip

Remove all the filters. Take a look, it's explorer.exe that is generating the hdd usage, querying stuff from throttlestop.exe every 9 seconds exactly. It only does that with throttlestop... That page has 20secs of monitoring my hdd.

[unclewebb]

TigTex: Thanks for showing me that. I have no idea why explorer.exe is constantly querying ThrottleStop. As I showed in my screen shots, ThrottleStop by itself is not initiating any access to the hard drive during normal use. It might be very difficult to track down what explorer.exe is up to but I will certainly look into this some more. I'm curious too.

e2zippo: You have to give me a few more details so I can help you out. What is your CPU model number and do you have a laptop? Most computers that use modulation will either use clock modulation or chipset clock modulation but not both so there is no need to check off both. You only need to check the one that is dropping down on your computer. Before checking anything I'd run a log file and test for throttling. No use fixing something if you don't have a problem.

To under volt using ThrottleStop all you have to do is put a check mark in the Set Multiplier box, maximize the multiplier and decrease the voltage until you lose stability. I usually do some brief tests with Prime95 Small FFTs when testing for basic stability and then when I see what the CPU is more or less capable of, I do longer tests after that. Some of the other settings depend on what CPU you have.

[unclewebb]

ThrottleStop 2.00 Build 27
http://www.fileden.com/files/2008/3/...rottleStop.zip

I found a bug that I think was causing explorer.exe to check up on ThrottleStop on a regular basis. I'm not sure why but I found a way to work around this issue so it should be OK now. If you have any problems TigTex, let me know. Thanks for finding this.

[TigTex]

Everything looks fine now. Thanks for fixing the possible bug.

[preview]

I've got a Core 2 Duo P8700 and was wondering what a good starting voltage would be using ThrottleStop?

Looking at ThrottleStop's log when the machine isn't doing anything in particular the multiplier seems to rapidly switch between different values. I'm seeing numbers like 9.86, 9.75, 9.60, 9.61, 9.58, 9.54. It goes to 9.50 (and seems to stay put there) when I run a Prime95 test.

Why is this? Why is 9.50 seemingly magical when it's under 100% load? Does this mean that I should force the multiplier to 9.50 or 10.0 (which ThrottleStop defaults to) when attempting to undervolt the CPU?

Which of the other checkboxes should I check?

[unclewebb]

The P8700 has a default multiplier of 9.50. When both cores are in the active state, that's the maximum multiplier that you will see. This CPU supports Intel Dynamic Acceleration. When one core goes to sleep and enters the C3/C6 sleep state, the other active core can use the 10.00 multiplier. In Windows there will always be background processes waking up the second core. As soon as this happens, the maximum multiplier will drop back to 9.50. ThrottleStop is able to accurately calculate the average multiplier based on data coming from high performance timers within the CPU. When IDA is being used, it is normal for the average multiplier to be constantly fluctuating somewhere between 9.50 and 10.00. If you run a single thread of Prime95 you should see the average multiplier get close to 10.00 if you don't have too much other background activity going on.

If your laptop doesn't use clock modulation or chipset clock modulation then there's no need to check these boxes off. If you run a log file while fully loaded then you will see if either of these apply to you.

Every CPU is unique. Lower the voltage and only use as much as you need to remain stable. Run something simple like Prime95 Small FFTs and start lowering your voltage until you lose stability. When you lose stability or your computer locks up, you've gone too far. I don't waste too much time finding an initial setting and them after that you can run more benchmarks for a longer period of time to see how stable your reduced voltage really is.

A P8700 might be OK at 1.05 volts to 1.10 volts.