# My First OC. CPU Voltage readings confusing



## Priapismic (Oct 7, 2008)

Greetings,
May I ask for some help please;
A year after I built this system I now need a bit more speed due to heavy video encoding demands (13-14 hours at 100% CPU). I only wish to mildly OC with the stock CPU fan - not looking to max anything - just get a little more from what I have while ensuring components' long lives.

So I read many threads, and learned, then raised the Bus from the stock 333Mhz to 386, with all other settings on auto and while encoding a video, CPU-Z shows;

-core speed went from the stock 2500 to 2900. (good enough for me)
-FSB went from stock 1333 to 1544
-Vcore went from 1.176 to 1.27
-CPU temps went from 40°C to 41°C :smile:
-All 4 core temps stayed around 150°F :smile:
-the CPUs are only at 70% and the encoding is faster

Now, I read that lowering the CPU voltage in BIOS would lower the temps so, I reset it from [auto] to 1.25, BUT...CPU-Z showed the Core Voltage as *1.10, and encoding slowed a little*. I got scared and set it back to auto.
Did I do something wrong? Is 1.27 OK to leave it at? Why were the cores at only 70% but doing more work?

Sorry if my questions sound dumb, I'm trying to learn.

Oh, one last question; Why does CPU-Z show my memory sticks being different? Should I manually correct the lower one?


----------



## Phædrus241 (Mar 28, 2009)

You never said what CPU you were using. It sounds like a Q8000 or Q9000 series by the 1333 FSB and voltage, maybe a Q9300 judging by clock speed. Either that or a Q8300. Is that right?


The CPU needs enough voltage to stay stable. You have to balance voltage (and thus stability at higher clock speeds) with heat. If you're stable on auto then I would leave it that way. It won't hurt anything.

The discrepancy between the VCore in BIOS and the VCore in CPU-Z is due to something called Vdroop. It's actually a really complicated subject, there's a whole huge article over at Anandtech that I can find for you if you want. But basically it drops the Vcore so that when the CPU load changes you don't get voltage spikes that go over the rated voltage. Some people disable it, some people leave it as is. I'd leave it in your case.

The SPD isn't your memory info, that's just telling you what specific settings your memory is rated for at different configurations. You can pretty much ignore that page unless you're trying to overclock/underclock your memory. It's normal.



Have you stress tested your CPU using a program like Prime95? That's very important to make sure your overclock is stable. If your computer can run Prime95 for at least six hours without A.) Prime95 reporting an error, B.) the CPU temperature going over 70C, C.) blue screens/crashes, then you're pretty much guaranteed stable.


----------



## Priapismic (Oct 7, 2008)

@ Phaedrus2401,
Thank you for the reply. My system info is in my Profile as I did not know where else to put it. :4-dontkno
I have a vague idea of the Vdroop concept but I definitely will read the article. The funny thing was that the Vcore stayed at 1.10 from idle through full load during encoding. Which is pretty much full blast I think.
Thanks for the response on the memory; I'll leave it be.
And I'll leave the system at auto as it ran flat out for 9 hours with no problem.

I have Prime95 and will do a full stress this week.


----------



## Phædrus241 (Mar 28, 2009)

If you go to the User CP, then to "Edit Options" if you scroll down it will have a "System Info" section where you can put in all the info you want, it shows up as the "My System" drop-down underneath your name in your posts.












<- Check out mine


----------



## Priapismic (Oct 7, 2008)

Update:
Prime95 found no abnormalities following 6 hours with the CPU voltage set at 1.25, and there is not even the remotest possibility that I would ever be running this machine that hard for that long. But I returned the setting to Auto anyway, both because of your advice, and because I am very uncomfortable with all 3 monitoring programs reading 1.10 volts whether the machine was at idle or fully stressed by Prime95. Something unknown to me is occurring, that I believe is potentially harmful for the voltage to not change, *and* to not be displayed as what I had set in BIOS as 1.25.
Illogical.


----------



## greenbrucelee (Apr 24, 2007)

when you use a program like cpu-z you will see the voltage at lower than what you have set it to but if you start using a game and set the game into a windowed mode you will see the voltage rise on cpuz when the game starts running.

This is nothing to be concerend about


----------

