ddr4 ram 2400 mhz showing up as 1200 mhz

I recently bought 2 new ram sticks of 8 GB ram 2400 mhz in total, when i check my cpu-z it only reads as about 1200 mhz. Seeing as i cant enable xmp profile on a dell inspiron 5675, idk how i can get it to read as 2400 mhz.