That's weird because i have had two pny sticks for long time and they worked flawlessly crashing only appeared when i bought two moreThere is no PNY ram listed as supported by MSI for your motherboard...you may be having a compatibility issue. You can try setting the ram timings and voltage manually in the BIOS or replace the ram with something on the support list provided by MSI.
https://us.msi.com/Motherboard/support/B250M-MORTAR#support-mem-5
Is it mixing if i literally bought the exactly same rams that i allready had?so you are mixing ram.
should have said that with full system spec