Sony might have unlocked the PS4's 7th CPU core for developers, through a recent software development kit (SDK) update.

　　The alleged SDK update allows developer to use an extra core on the PS4's CPU, and was found in the change log for the most recent audio API FMOD update. The complete revision of the FMOD studio API, can be found here.

　　Firelight Technologies FMOD Studio API Detailed Revision History 17/11/15 1.07.03 - Studio API patch release (build 69975) Features: LowLevel API - When using System::recordStart the provided FMOD::Sound can now be any channel count, up/down mixing will be performed as necessary. LowLevel API - Improved performance of convolution reverb effect when wet is 0 or input goes idle. LowLevel API - PS4 - Added FMOD_THREAD_CORE6 to allow access to the newly unlocked 7th core.

PS4 CPU

　　Main competitor Microsoft, unlocked the 7th core for their Xbox One, in January of this year. Due to access to the 7th core, developers were able to use more processing power for their games. According Eurogamer, "the ability to tap into more processing power could perhaps explain why Assassin's Creed Unity runs smoother on Xbox One than it does on PS4, and also why traffic-heavy junctions in GTA 5 see a smaller hit to performance on the Microsoft console. It may also explain this curious presentation slide from the developers of ACU, showing a 15 per cent CPU advantage to Xbox One compared to PS4".

　　Interestingly enough, if you would check the above mentioned FMOD revision, you would learn that, the revisions mentions the access to the 7th core of the Xbox One as well.

　　22/01/15 1.05.11 - Studio API patch release Features:\ Lowlevel API - Xbox One - Added access to 7th CPU core.

　　The Xbox One uses the same architecture as the PS4 does, but has a custom Jaquar eight core CPU clocked at 1.75GHz.

　　Sony's hasn't confirmed anything on unlocking the 7th core of their console, so for now, this remains a rumor - a nice one nonetheless. Let's hope the rumors proves legit, so developers will indeed be able to access more CPU power on the PS4.

　　Thanks DieH@rd from Neogaf, an amazing find.