Question win 7 os , intel H170M D3H GIGA CPU intel i5 6402 not recognizing more than 16 GB Ram

[siva_n]

Hi,
for my desktop running on Win7 ultimate os , intel H170M D3H GIGA , with CPU intel i5 6402 @2.8ghz- 6the gen , the ram installed isG skill Ripjaw2 x DDR-2400 PC4-19200 8192MBx1; F4-2400C 15S- 8GVR ; showing 16GB ram in my compute properties .Recently installed another Gskill Ripjaw DDR4 Memory Module (8GB X 1pcs, 3000Mhz);now also the properties shows only 16 GB instead of 24 GB.what could be reason , does the new installed DDR4 Memory Module (8GB X 1pcs, 3000Mhz) is incompatible ?Thanks in advance for the suitable answer.

 

[rgd1101]

does it work if you only have the new ram?
mixing ram sometime work. sometime don't