Issue with upgrading RAM on xps 15 9550

Hi everyone, I'm trying to get my wife's xps 15 unable again, and have run into a strange issue. I bought 2x16 GB Kingston Fury DDR4 3200 MT/s, and am trying to install them. According to the website they should work. When I started the laptop with both installed, the Fan starts, run for 30 seconds or so, and then it turns off. The only configuration that works is to use one of them with one of the old ones, (for a total of 20) GB. What I've tried: - switching them around (both new RAMs work in the 20 GB configuration) - running them single - does not work - the obvious stuff. leaving it unplugged, with battery unplugged etc.

Any ideas would be welcome, I have run out of them at this point. Thank you!

EDIT: Ordered new RAM bars (2400MHz) and they worked immediately without any issues.