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Hello everyone, in the last class we looked at the working conditions of DDR3 memory

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In this lesson, let's take a look at the working conditions of DDR4 memory

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The first is VDDQ, the memory main power supply

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Its voltage is 1.2V

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It is better to measure it at the memory power supply inductance

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Next is the VPP

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VPP is an extra voltage of DDR4 memory, and its voltage value is 2.5V

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This voltage can be measured on pins 142, 143, 286, 287 and 288 of the memory slot

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So where are these pins?

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Let's take a look at this memory slot

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We must first distinguish between upper and lower

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In general, those near the South Bridge are down,

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and those far away from the South Bridge are up.

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The pin division of DDR4 memory is from top to bottom

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It has 144 pins on one side, and a total of 288 on both sides

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The power supply of VPP is at pins 142, 143, 286, 287 and 288, all of which are below

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We can measure directly on 288 pins

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Next is the VTT power supply

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The VTT power supply of DDR4 memory is also half of VDDQ

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VDDQ is 1.2V, then VTT is 0.6V

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It can be measured on pin 77 and pin 221 of the memory slot

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We take the anti-fool gate as the boundary,

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and the ones next to the anti-fool gate are 77 pins and 221 pins

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We can measure it directly here

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The next is reference voltage

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The reference voltage is the same as the VTT voltage, 0.6V

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It can be measured from memory to pin 146, which is the second pin from top to bottom on the right

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Next SPD power supply

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DDR4SPD power supply has two voltages, some mainboards use VPP power supply, 2.5V,

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such as Gigabyte

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Of course, more mainboards use 3.3V

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It can be measured on pin 284 of the memory slot

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Further down, the SM bus, it needs to have a waveform

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But if there is no oscilloscope, we can measure the voltage, a voltage of about 3.3V is enough

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It can be measured on 141 pins and 285 pins

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The last one, memory reset

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The memory reset is on pin 58 of the memory slot

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This pin is hard to find

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It is pulled up by the memory main power supply VDDQ

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We use a multimeter to measure, and we should be able to measure a voltage of 1.2V

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If these conditions are met, then we need to check whether the memory slot has oxidized pins

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Install the CPU at the same time, and measure whether the data lines are connected

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The above is the maintenance process of DDR4 memory