russell_84 :
is it better to have a single 8gb ram stick or two 4gb ram sticks and what are the pros and cons if any?
The number of DIMMs isn't important. What's important is the following:
1. The number of populated memory channels. Each memory channel is independent and each memory channel can be accessed concurrently. This provides up to twice the memory bandwidth.
2. The number of ranks per channel. Consumer DIMMs typically have one or two ranks per DIMM. Two single-rank 4GiB DIMMs with one 4GiB rank each are logically equivalent to a single dual-rank 8GiB DIMM constructed from two 4GiB ranks.
A minimum of two ranks per channel (at least one dual-rank DIMM, or two single-rank DIMMs) is recommended. The upper limit is four ranks on consumer motherboards. Performance will increase with each additional rank until the maximum number supported by the memory controller's look-ahead logic is reached. Intel's current-gen memory controller can handle 32 open pages per channel which corresponds to four DDR3 ranks. Adding more ranks (possible only on workstation and server motherboards that support registered memory) will increase capacity but not performance.