Upgrade memory RAM - HP ENVY Notebook 15

[lbonifazi]

Hi All!

Last weekend I updated the memory RAM of my laptop HP ENVY Notebook - 15-k277ca.

The machine has 1 module of 8GB by factory, so I've bought another module of 8GB (same Brand and same rate).

But the problem is that the machine did not recognize this second module, neither in BIOS nor SO.

Currently I'm running Windows 10 Enterprise x64.

The weird part is that I've downloaded the CPU-Z, and this software recognizes the two modules.

Any idea?

Here are the image of the CPU-Z software (where the memories are recognized)

[Huffer · Accepted solution]

See the voltages? You have mixed low voltage and regular voltage memory. They may be the same maker and speed but they are not the same voltage. This will cause issues as you are seeing. The computer is designed to run DDR3L (1.35 volt) memory. When you match modules you really have to match modules. Can you confirm the part numbers printed on the two modules and the specifications stated on the labels? 

[lbonifazi]

Thank you so much for your quick response. I see it was my mistake, I've not consider the voltages.
So my question now is, should I buy another memory bank with the same part number, or it is OK if just it matches the maker, speed and voltage?

[Huffer]

Same part number is best. You also need to consider density (8 black blocks on side or 4) and latency specs so the safest is to buy 2 identical modules.