The 930 is really no better then the 860 the cost really comes down to X58 vs P55 and how much RAM you need so for 6GB or more like 9GB or 12GB go X58 for 4GB or 8GB go P55.
True you can run 4GB or 8GB on a X58 but its a bit pointless.
maximum multiplier for both is 21 without Turbo Boost.
I would recommend going with an i7 processor due to the hyperthreading speeds it has over the i5. With the processor you choose it will come down to the amount of RAM you are wanting to use. If you want to have two sticks of RAM then go with the 860 since it supports dual channel memory and will utalize the memory better. If you plan on having three sticks of RAM go with the 920 due to its support of triple channel memory/
