I believe that one of the biggest challenges of PS4/X1 is the efficient use of the 8 cores on their CPU.

The single thread performance of Jaguar cores are not that good (which is expected since one of its targets are Tablets and Netbooks). It also does not have something like Intel's Turbo Bust to improve its single thread performance by a dynamic/on-demand overclock. To offset these limitations, developers have the option to parallelize their CPU intensive code.

Unfortunately to create such a code developers have to face some interesting problems:

1) Not every task can be parallelized;
2) Some task can be parallelized but the result is a code that runs slower than the original code;
3) Once parallelized a code becomes non-deterministic which may lead to a lot of trouble to test it;
4) Data synchronization (starvation, racing conditions, deadlock, etc.);
5) Using 100% of 8 cores at the same time is almost impossible unless you are coding a solution to something homogeneous like weather forecast;

By the way, I read that since their CPU is essentially two independent Jaguar combined hence the CPU may not be suited to allow a process to have access to the 8 cores at the same time (four cores for each process), can someone please confirm this to me?

I'll admit, I'm no expert in CPUs, but the enemy counts in Dead Rising 3 are enough to convince me that Jaguar's got the goods. I think it says a lot about the strength of PS3/360's CPUs that in 2013, 7-8 years after release, they're still up to running most of the top games, including ports from PS4/X1.

Most of the problems you listed developers had to face this generation with the Cell and it's SPU's, except that it'll be much simpler to code for due to the architecture and you don't need to write custom code like you had to do with the cell, and yeah I also heard they were basically glued together, but I doubt any process would need more than four cores. 

and most devs failed at it pretty badly most of this gen, typically multiplatform games would use 1-2 cores on X360 and just the PPU and very little code on SPEs on the PS3 (why most early PS3 ports performed like shit). It's only in the last 3-4 years that devs have really started to get the hang of highly jobified engines. Hell look at Killzone 3 90% of game logic and 80% of AI code was not jobified and run on just the PPU. With the SPUs mostly being used for AA (eg highly parrilised code that would be better suited to a capable GPU), rendering code (80% was jobified) and some physics, and their engine was designed specifically for the PS3 and was one of the early engines to push a heavy job bassed system. Of course with shadow fall they claim that their engine now jobifies 90% of rendering code, 80% of AI code, and 80% of game logic so they are doing much better now and SPEs sucked at most general code anyway. But also the fact that good GPUs with decent GPGPU capabilities in next gen means that a lot of the highly parrilised code will actually be moved off the CPU in the future, and you want see many devs doing graphical effects on the CPUs.

and most devs failed at it pretty badly most of this gen, typically multiplatform games would use 1-2 cores on X360 and just the PPU and very little code on SPEs on the PS3 (why most early PS3 ports performed like shit). It's only in the last 3-4 years that devs have really started to get the hang of highly jobified engines. Hell look at Killzone 3 90% (just 10% jobified) of game logic and 80% (just 20% jobified) of AI code was run on just the PPU. With the SPUs mostly being used for AA (eg highly parrilised code that would be better suited to a capable GPU), rendering code (80% was jobified) and some physics, and their engine was designed specifically for the PS3 and was one of the early engines to push a heavy job bassed system. Of course with shadow fall they claim that their engine now jobifies 90% of rendering code, 80% of AI code, and 80% of game logic so they are doing much better now and SPEs sucked at most general code anyway. But also the fact that good GPUs with decent GPGPU capabilities in next gen means that a lot of the highly parrilised code will actually be moved off the CPU in the future, and you want see many devs doing graphical effects on the CPUs.

But both the Xbone and PS4 will use the same chip this time around, so angling the CPU should be easier so I don't expect to see bottlenecks coming from the chip's layout, but then again with devs like Bethesda you never know.

No offense to any amd fans in here but their CPUs blow ass compared to intel chips. Yeah I understand there are price differences between the two but that doesn't change the fact that second gen I5 CPUs will still crush 8-core amd processors. I still don't understand why they didn't just drop in second or even the low end third gen core I5 CPUs in these machines.
The simple fact that they use these garbage CPUs makes me question the true performance of the machines. Again no offense to amd but if a chain is only as strong as its weakest link then it's these CPUs. Hell I would bet my old q9550 would be a better choice than these and that's a 6-7 yr old processor.

On a side note I was watching some reviews of the new seiki 4k tv which retails for 1200$ yeah 4k for 1200 it's kinda crazy. Anyway crysis and BF4 on max out settings we getting shit FPS on sli 680gtx cards, which are miles better than the gpus coming in next gen systems. I'm wondering how they plan on pushing 4k gaming with "next gen" looking games. Someone care to explain? I just don't see this hardware accomplishing this.

Next gen consoles aren't going for 4K gaming, they're 4K Video playback only. 

Also, no one in this thread said they're better than a second gen i5? Did you even read the thread or did you simply come here to bash the consoles? , please don't bother replying unless you plan on adding something actually relevant to the thread, rather than trying to troll by mentioning graphics AND A FUCKING GAME THAT HASN'T EVEN CAME OUT YET, neither has anything to do with the topic.

Modern games are not CPU demanding. For instance, if you have a code that has a lot of float point operations and it is running on the CPU you probably are wasting resources since the GPU is much more suited to perform this type of operation (consequently the game becomes even less CPU demanding).

This is why also think that 4 Jaguar cores and even 3 PPC 750 cores maybe more than enough to the next gen games (btw notice that the Wii U CPU was made for lazy developers since one of its cores has more cache, enabling single thread code to run quite well on it).

And finally, since Sony and MS decided to use only half of the CPU (4 cores) for games this maybe a hint to an OS with lots things running on the background (perhaps they are working on even more features for the SO than what we know so far).

yhnak you