The H and B boards are practically the same thing, as the H series boards have "slightly" more features here and there depending on the board in question. It's not worth the extra cash IMO where you can get other things that are better like the difference between the 4670k and 4430 on saved money.
Also on the cache, real world differences are not seen. I have a 1TB Seagate 64MB cache, and 1TB 32MB cache Seagate in my machine right now and sustain/burst speeds are exactly the same. When used as an every day drive it's still moot. The cash is better spent on the CPU as the 4670k will last you quite a while and you can simply upgrade the GPU later or better yet just buy an SSD when you have the money. Which I recommend you doing asap anyways.