Teach you to use a multimeter to measure the core voltage

In the daily use of computers, we all judge the operating status of the computer through the data reflected by the sensors on the computer. Have you ever considered whether the displayed data is accurate? Some extreme gamers like to overclock the graphics card. When overclocking to the extreme, they will record every voltage and frequency change. At this time, the hardware is already in an overloaded state. The slightest carelessness may cause permanent damage to the hardware. At this time, accurate core voltage is very necessary.

For transistors in graphics cards, the necessary threshold voltage is an important factor for the normal operation of the driver. If you want the chip to work at a higher frequency, a sufficiently high voltage is a necessary basic condition. Therefore, voltage is the data that players care about most when overclocking.

Software can display core voltage

At present, the core voltage parameters can be displayed intuitively by software, and the data read by the software comes from the internal sensor set by the graphics card manufacturer. But when it comes to measuring voltage, as a science and engineering man, the editor thinks of a multimeter. Can we use the multimeter commonly used in life to measure the core voltage of the graphics card? The following is our test.

The GALAX graphics card I have now has some voltage measurement points, which are located on the side of the SIL gold finger of the graphics card. There are five points in a row, marked with "GPU-V", "DDR-V", "GND", "PCI-V", "5V", etc. According to experience, these represent the GPU core voltage, video memory voltage, ground, PCI slot voltage and graphics card fan voltage.

The voltage measurement hole is on the right

To measure voltage, we first need to prepare a multimeter, then adjust the multimeter to zero, so that the error can be minimized, and then adjust the multimeter to the DC voltage range to indicate that the DC voltage is measured. Some voltmeters may require you to select a range. The voltage of a graphics card is generally around 1V, so you need to select a smaller range.

The top measurement hole is covered by the back plate

When preparing the graphics card, we found a problem. There are five measuring holes in total, but the top hole for measuring the core voltage is covered by the back plate of the graphics card. The back plate of the graphics card must be removed for normal operation. I don’t know whether this is an intentional design by the manufacturer or an unintentional mistake in designing the back plate. Considering that only extreme gamers will measure the core voltage, and the back plate is generally removed when performing this kind of overclocking, we believe that this is an intentional design by the manufacturer.

Next, we will start to test the voltage on the machine. We will install the graphics card on the test platform and turn it on. Then connect the black pen of the multimeter to the end marked as "GND" and the red pen to the "GPU-V" port. The multimeter will display the core voltage value. If you want to measure the voltage value of the video memory, just connect the red pen of the multimeter to the "DDR-V" end. The same method can be used to measure other voltages.

The measurement method is as shown in the figure

On-the-machine test

We open GPU-Z and AIDA64 software, both of which can display the GPU core voltage, but we find that their values ​​are actually the same, which means that they are actually calling the same sensor. Then let's take a look at the voltage displayed by the software and the voltage measured by the multimeter under standby conditions.

The voltage under standby condition is as shown in the figure

From the figure, we can see that the values ​​of the two are basically equal under standby conditions, which shows that our test method is still applicable. Then we open the baking software and let the graphics card run under high load. At this time, the graphics card will adjust to a higher voltage to achieve a higher frequency, and the displayed values ​​begin to differ. The comparison of the two is shown in the figure.

The voltage under the baking environment is as shown in the figure

It can be seen that the data measured by the two are still different. The voltage measured by the voltmeter is generally greater than the voltage measured by the internal sensor.

In this generation of Maxwell core NV controls the core voltage more strictly, so we cannot use software to increase the core voltage to verify how big the difference is between the two, but it is undeniable that there is indeed a difference in the measured voltage between the two.

Other players use a multimeter to measure voltage

The values ​​read by the sensors inside the core used by the software are generally more accurate. However, the voltage detection point is not at the most accurate position on the core input and output circuit. It is usually placed on the periphery of the PCB for easy routing and use. Therefore, the input and output voltages of the core may be interfered by other components on the circuit. Especially in the case of high power consumption, the voltage used by other components on the circuit will also increase, so the measured value is too large.

Measuring points are on the outside of the graphics card for easy access

In addition, we use a digital multimeter here, and the highest voltage that can be measured can reach hundreds of volts. Every digital meter has errors, so when measuring voltages of only a few millivolts, the error becomes more obvious. This is another reason why the two display differently.

As mentioned above, the core voltage needs to be strictly controlled during extreme overclocking. So, in addition to software display, what other methods can be used to obtain the precise voltage? Some advanced overclockers use external instruments to measure the core voltage by flying wires on the PCB or finding solder joints for measurement. Therefore, we can see that the graphics cards of advanced overclockers are connected to various wires.

Advanced Gamer Overclocking

So if you want to know the precise core voltage, you first need to find the exact measurement location, and then use an accurate voltmeter that meets the range. These are too expensive for ordinary users and not very meaningful. Therefore, most users use the value displayed on the software. But this function is not completely meaningless.

Measurement points for other graphics cards

For example, the video card can also measure the memory voltage, which is a value that cannot be displayed in the software. This is also a very important data for overclocking players. In general, with the increasing homogeneity of graphics card products, the addition of these new functions has improved the playability of graphics cards. Perhaps more and more novel and interesting new functions like this will lead to more interesting discoveries.