The R9 380 in some games will be bottle necked by the Phenom II x4 965 be processor. It actually bottlenecks some games with a HD 7970/R9 280X so it will surly bottleneck a faster GPU.
On this I speck from experience as I have the Phenom II x4 965 be OCed to 3.957 GHz and a HD 7970/R9 280X GPU in my gaming system. While I can play most games fine certain games need the graphics turned down to compensate for the weak CPU. Games like Crysis 3, Far Cry 3, Bioshock Infinite, Resident Evil Revelations 2, Battlefield 4 ect.