at first I bought corsair vengeance lpx ddr4 4gig 2400mhz with serial number cmk4gx4m1a2400c14 cz that's as far as my budget goes. then I want to upgrade my ram but still want to use my old ram. then I read some article that mentioned some serious problem of incompatibility bsod etc even when the same brand of ram is paired. what if I buy the exact same ram as my old one? will I still have some problem? thanks for answer