First answer, WHats difference b/w suzuki fx and mehran and alto and vvti and 911 turbo and lamborghini and bugatti?
hint: the bigger the size/cost, the higher the performance/tweaks.
Sir, do you even know what you're talking about? An i5 2500k/2500/any other LGA1155 processor at stock will perform the same at H61 H67 P67 Z77 Z68. EXACTLY the same.
Yes, you're correct in saying that you'd have to pay a higher price if you want to overclock, but the higher price does not say higher performance.
Secondly, buying a z77 board with a 2100 would be sheer stupidity. In your metaphorical example, running a Lamborghini at a 30kph speed limit road only. Therefore, going for
Big bucks doesn't always equals higher performance. All expensive things need not be steller performers.
Lastly, which board and chipset depends on what his processor is or what his intentions are. Currently, even a 2500k maxes out everything at human resolutions and a decent gpu. Overclocking will only be needed if either the person is an ock freak, or is going to run insane setups with multiple high resolution displays.
Anyway. @OP, over the top of my head,
H61 :
Entry level.
2 DIMM slots
Usually 1 PCIe 2.1 slot
Ideally no provision for SATA 3 (can be used via SATA3 cards though I hear)
No ocking possible of any sort
1333 MHz RAM supported (Sandy Bridge and Ivy Bridge don't benefit from faster RAM anyway.)
H67:
Usually 4 DIMMs
Ideally comes with SATA3 connectivity (Very useful if you have a SATA3 SDD. Not worth it if you have a SATA3 HDD though as it is bottlenecked by the HDD hardware anyway)
Ocking the processor is not possible however you can overvolt and thus overclock your GPU
1333MHz memory supported only
PCIe 2.1 slot(s)
P67:
H67 minus overclocking your GPU but you can overclock your processor (UNLOCKED PROCESSORS ONLY, the ones which have a K at the end of the number)
Z68:
H67 + P67
In that, everything they offer, so you can overclock the processor aswell as the gpu
Z77:
Almost a Z68 that was introduced for ivy bridge processors (3xxx)
PCIe 3.0 lane(s)
basically, one should opt for a z77 board if they plan on gaming on an insane resolution of multiple displays such as 5760x1080, 7860x1600 etc where you would require the higher bandwith which top end cards like the 7970, 680 4gb etc would consume. Memory bandwith stays the same in multiple GPU configs so initial higher is helpful.
Anyway. Concluding, I'd say stick to H61 if you are a normal gamer and not a benchmark freak, have no plans of overclocking or imminent plans of SATA3.