How to measure Vcore with a voltmeter?

[rustynator]

I am going to try and use this picture below in conjuction with my voltmeter to try and check whether my bios or CPUz is closer to the actual Vcore through my CPU. The picture doesnt make it very clear where to stick the 2 probes though, do I just pick one of each of the three Vcore and Vground spots at random? Cheers

 

[supershanks]

Yep black to Ground & red to any of the Vcore points.

 

I did this recently, initially i felt a bit unsure & so pushed the ground probe into a molex ground pin (black). This enabled me to focus on placing the red probe properly. This method may not be as accurate due to resistance. But i later repeated it using the ground & vcore as in the picture & got the same reading.

 

luck

[Kandoo]

So the ground does not have to correspond with the test point? just ground the black lead and test the other points with the red lead. is that correct.

[rustynator]

When you say ground do you mean Vgnd or Ground? What is the difference between the 2? Also if were to make a mistake how much dame could I do?

[supershanks]

Yep

I asked 4 confirmation 1st (not being an electrical expert

See

How can i measure

&

The master's Answer

 

This is also handy

How to measure your rails

 

luck

[Kandoo]

You dont want to short one probe across (touch both at the same time with one probe) both points. still not clear on Vgnd/Ground.

[supershanks]

I didn't use vgnd at all. Just Vcore & Ground.

 

Also if were to make a mistake how much dame could I do?

you can take out your mobo.

 

Hence it's something to do very carefully & why i was initially wary of using both probes relatively close to each other.

 

Edit:

Also see Testing Your PSU Voltage Rails

[rustynator]

Thanks a lot. I will try your safer method first then if I am feeling adventurous I will try the danger method. What were you findings? Was the Vcore closer to windows or bios?

[rustynator]

p.s. I take it doesnt matter which way you connect the probes (i.e. black for Vcore and red for ground and vice versa), one will give a positive voltage and the other a negative reading.

[supershanks]

Vcore was spot on what you set it to in bios, the reading in bios was slightly understated whilst windows readings significantly understated the actual vcore. The really significant variation was Vdimm which read over the bios setting :-

2.6v = 2.66v

2.6v +.03 = 2.71v

2.7v =2.78v

2.7v +.03 = 2.81v

2.8v = 2.88v

2.8v +.03 = 2.91

 

cheers

[rustynator]

Right...I have taken the readings by the proper way (not the molex way) and they show that you CANNOT trust windows in the slightest. I set the Vcore at 1.525 in the bios. In windows it shows up as 1.52V, in the bios it shows as 1.54V, but the voltmeter reads 1.55V when idle and 1.57V when on full load. THat is a difference if up to .05V!

 

Now for the Vdimm. In the bios I set the Vdimm at 2.70V. In windows this value reads 2.7V, in bios it reads 2.74V but on the voltmeter it reads 2.77V at both idle and load. A difference of 0.07V!

 

This just proves how unreliable both the bios and windows are at reading voltages.

[soundx98]

Now you have to ask yourself.

 

Just how hard would it have been to put some easy to probe and labeled test points on these overclockers boards.

Little deal labeled "Test Point" for us thick fingered types that a probe would make contact with easily.