In nvidia make sure you change some options in the 3d/management, you can set the monitor to single display as by default its set to multi monitor
I also personally set the quality and performance more toward performance since quality has been getting increase on the media itself
Is it only when you play media thru disks, cause if that's the case the optical drive and what your using to play the video may be the culprit and not the PC itself, since the drive actually opens blurays you can assume the certificates weren't removed so that's good
Also with a new PC you shouldn't have needed any codecs, if you installed any that's possibly the issue as well
Typically all a newer machine needs is its settings adjusted and VLC Media player, regular if using 32 bit and the 64 bit version if that's what OS you have, I had choppy video when I accidentally installed the 32 bit version on my 64 machine
CoolerMaster HAF 932 Advanced/ Maximus VI Formula/ I7-4770K/Swiftech H320/ Corsair HX850/ G.Skill Trident X (2x8) 16gb 2400MHz/ 2x 840 EVO 120gb(Raid 0)/ WD 1TB HDD (Backup/Storage)/ EVGA GTX 1gb 560 TI/ Asus 12x bluray combo