XPS 15 9500 doesn't boot with memory upgrade

Recently bought  a pair of 16GB GSkill Ripjaws (DDR4-2400mhz) for my xps 15.

After slotting them in the laptop won't post and the power indicator flashes orange twice then white four times.

I then put the original DIMMs back in and it runs completely fine.

So I plan on sending them back and finding a pair of compatible sticks but they're isn't a lot of documentation on
memory that actually works.

Any suggestions?

Thanks in advance!