Truth be told, it matters little.
Faster ram is accompanied by higher latencies, negating much of the speed advantage.
Synthetic ram benchmarks can point out differences, but the difference in speed is hard to detect in actual app performance or fps.
Think 1-3% between the slowest and fastest.
With intel cpu's, speed matters little.
With amd cpu's it matters more.
Here is a good article on haswell ram scaling:
http://www.anandtech.com/show/7364/memory-scaling-on-haswell
And... fancy heat spreaders are mostly marketing.
Ram vendors have found out that they can charge more for looks.
They are only useful to enthusiast overclockers seeking to find the fastest ram.
They actually hurt because they can interfere with some air coolers.
Buy low profile ram.