Question Corsair Vengeance LPX 16GBx2 installed, windows shows 15.9 GB usable

[sandeeptiwari]

Hello Everyone,


My Rig is:
AMD Ryzen 1600x cpu
MSI X370 Gaming Pro motherboard with latest
Windows 10 Home 64 bit
GTX 1070 8GBx2
Earlier had 1 Corsair Vengeance LPX 2400 Mhz 16GB DDR4 RAM (CMK16GX4m1A2400C16), and all is working fine.

Yesterday I installed another RAM of same company and configuration (CMK16GX4m1A2400C16), the problem stared, that
BIOS shows just 16384 RAM whereas Windows shows 32 GB but just 15.9 GB usable.

Applied MSCONFIG - Advanced - Unchecked option - Result does not change
Applied XMP Profile 2 2400MHz in Bios - Result does not change

Applied Latest BIOS update 7A33v4IO on motherboad, result does not change.
Applied RAM changed Ports as well as change in A1 B1 & A2 B2 slots - Result does not change

Please Help me to let me know how I can use this additional RAM with windows using both 16GB RAMS.

I shall be really grateful for your timely help ??

P.S.:
There's one change, when checking with CPU-Z with DRAM manuf in 1 Shows as SK Hynix and another it shows as SK Micron

 

[jojesa]

It is hard to predict the outcome when you mix and match stick that may have different speed, CAS latency, timings, voltage or IC chip, since they were not tested to work together.
Half of the time a computer will run just fine when mixing different brands, sizes and speeds. Motherboards, automatically, underclock the faster RAM stick to match the other, so you wouldn't run into any issues.
Even when they appear to be similar, the IC chips might come from different manufactures, as you found out in CPU-Z.
There are times when the motherboard just refuses to work with different RAM modules.
To be sure that RAM will work together you will have to buy RAM kits.
That's why manufacturers and vendors won't provide support for that configuration.

You could manually set speed, CAS latency, timings and voltage in the BIOS to get them to work together.
Make sure RAM is installed in slots DIMM A2 & DIMM B2 (slots 2 and 4 from the CPU).

 

[sandeeptiwari]

but the model # of the chip as provided by Corsair is same as 16-16-16-39, with same lateny too and volatge is at 1.84 too. Cannot it be used in same rig - bcos i purchased both rams sperately, and I cannot ask a dealer to open every packet for me to check whether its hynix or micron !! any other option by which both will be shown in BIOS as well as used by Windows, Suggest me seperate alternative, instead, which helps. Advanced Memory Diagonistc Tool also does not repoert any errors for bioth in standard test format too.

 

[jojesa]

.... bcos i purchased both rams sperately, and I cannot ask a dealer to open every packet for me to check whether its hynix or micron !!

If you buy them separately there is no way to know until you install them.
That is the main reason to purchase RAM kits, which have the same IC chip and have been tested to work together.

any other option by which both will be shown in BIOS as well as used by Windows, Suggest me seperate alternative, instead, which helps.

As I previously suggested, you could manually set speed, CAS latency, timings and voltage in the BIOS to get them to work together.
Make sure RAM is installed in slots DIMM A2 & DIMM B2 (slots 2 and 4 from the CPU).

 

[Calvin7]

Corsair does not guarantee such combinations that you have to be compatible together. Since you can make any combinations you want, you can do your own compatibility testing with no guarantees.