http://forum.xda-developers.com/showthread.php?t=1831780
use this kernel

You have a lot to learn my friend. Don't be lazy

to get you started.

1) Which kernel is the most stable for your Nexus 7? - you have to tried it yourself. Every device are indeed the same but the hardware capability in taking higher clock processing speed is different in each device. Therefore some of us probably have witness artifact at 1800/700mhz speed but some of us might have not.

2) Is everyone in this thread have already overclocked their Nexus 7?
- Most probably yes if they're using custom rom/kernel. But I doubt most of them run at the level of 1800mhz.

3) How is the benchmark?
- Difference by a lot. Without a hard overclocking kernel our N7 are behind HTC One X and Asus Transformer Prime. But once you get on into a custom modded kernel for our devices...behold 

4) Can you use that kernel on your Samsung Galaxy W or your china tablet?
- No.no.no.no. Unless you write the kernel yourself..still it won't run. Trust me. no.