I think the overclocked Pentium will dominate up in games that would use up to maximum of 4 cores (making it perfect as a mmo, Steam machine or a lounge casual gaming PC); games that use higher number of cores, the overclocked FX6 will take the lead. But to be honest, anyone who is going use a PC for serious gaming on demand titles you mentioned above, they would most likely invest(ed) on at least a FX8320 or a i5-K anyway. Think we just need to wait for benchmark to see it in action for real.
I think the idea of the Pentium-K and Z-motherboard combi is that it would offer those who need just the right amount of CPU grunt of the games they are playing right now, and should they want to get into playing more demanding games, they would have the option to upgrade to a i5 or i7. And at the end of the day, I think the Pentium-K would make a interesting novelty item as a collection for the future as well
The problem is that reviews have tested the latest G3420 in some more demanding games,like the ones I mentioned,and even if you assume perfect clock scaling I am not sure how well they will do. The CPU is also limited to 1333MHZ DDR3 RAM and lacks multiple extension support,ie,things like AVX2 and the like.
People forget the E8400 vs Q6600 arguments years ago. The Q6600 won that one ages ago.
The same goes with the Core i3 530 against the G6950 and so on.
Edit!!
Its like this test of Thief over on Anandtech forums:
http://oi60.tinypic.com/x37q0j.jpg
http://oi58.tinypic.com/2nivdli.jpg
Chap reported the G3420 also had very spikey gameplay even with Mantle enabled which helped all other CPUs,meaning we need to consider how bad the latency will be too.
Even with a 40% overclock,the Core i3 will provide a better experience in the game.
That is the latest UE3 based game too which is an old engine. Longterm I am not sure how it will pan out TBH,especially with ALL the next generation engines threading quite well and DX12 and Mantle improving threading too.
OTH,you could just get a cheaper B85 or H81 motherboard and get a Core i3 and have better performance in newer titles,and capable performance in older ones,or get an FX6300/FX8320 if your bias is more towards newer titles and less demanding older ones.
It might do well for some games which are very lightly thread and very CPU intensive(but many might be lightly threaded and still not really push any newish CPU still like DOTA2) or some emulators,but many games are now pushing at least three to four threads now.
With dozens of devs aboard the Mantle bandwagon and DX12 being released in the next year or so and the console factor,the competitive landscape is changing quickly IMHO. Look at this for example:
http://wccftech.com/mantle-api-ported-directx-12-amd-white-paper/
Look at the improved threading of Nvidia drivers too.
The thing is a Core i3 K series would have been awesome,but probably reduced Core i5 sales a decent amount.
A £90 Core i3 K series would have excited me much more.
That could have potential to match a locked Core i5 in MT performance too,while being slightly cheaper even with a overclocking motherboard and cooler.
Not having a dig, just speculating.
Do you actually need a Z series board to overclock though. A couple of months ago i built a pc for the wife using a Gigabyte B85M-D3H and even with the latest bios it still has overclocking options. The month before i built a pc for the sister in law using a Asrock H81M HDS and even that has a few overclocking options still in the latest bios. They can't be used with the Pentiums that i got them both but surely they would clock a K series cpu such as the Pentium anniversary edition?
http://www.bit-tech.net/news/hardware/2013/07/25/intel-overclocking-block/1
Its at the CPU level.