I am looking to get the 4670k soon and the h100i, what are your recommendations for overclocking? I am new to overclocking so what programme would i use? My motherboard is a ASRock Z87E-ITX, i have a corsair 750 watt modular psu, and a bitfenix prodigy itx case.
Also is the 4670k and the Sapphire R9 280x a good combination for battlefield 3/4. if so, what fps would i get?
With the H100i, you could overclock to about 4.6 GHz if you get a "good chip" because the quality of the chip partially depends on the batch quality that they made. The Haswell processors are great, but they are a bit limited in overclocking. VCore should end around 1.2-1.22 I think. I have the H60, so I haven't tried to get that high. You don't need any software to overclock. It is done in your BIOS, and if you are new to overclocking, take it slow. Go up to like 4 GHz, and figure out the voltage for that with testing with Prime95 or some other CPU stress test. Get to the best stable clock with the lowest stable voltage. Work your way up to 4.4-4.6 GHz. If something goes critically wrong, clear your CMOS, and start again. You will get decent fps on BF4, but don't expect the world because it is a very taxing game.
To overclock, go into your BIOS, raise your multiplier, customize your CPU voltage, and don't touch anything else depending on your motherboard. If your motherboard has features for power saving, turn it off. Those can interfere with overclocks. Run Prime95 for 2 or so hours to see if your CPU gets any errors or freezes. If that happens, adjust the voltage. If it's a freeze or some other power error, raise your voltage ever so slightly. If its a shutdown or an overheating problem, lower it. Once you get a voltage that returns no errors, lower it until the last stable voltage. This is how I've done it with that processor, and it worked fine at a much lower clock than yours. GL and don't ever move the voltage by more than 0.05V at a time when adjusting.
Hard to say, but I would say around 50-70 depending on settings and what's happening in the scene. It probably won't be ultra quality though. More around high with some added features such as better antialiasing.
Getting 4 GB more RAM couldn't hurt, but the CPU and GPU won't bottleneck each other. That all is fine. The RAM might bottleneck your CPU depending on their speeds, but I could be wrong about that. All in all, those are two great pieces of hardware.