Of course ram temps matter. Its just the overall effect of the system that adds yet another heat source to the PC in general The whole system cooled and desired effect is to maintain a level where all can work well. Ram temps are very basic int. ones and when thought out, they generate within themselves and have only the surrounding cool air to help keep it cool. The process of using ram heatsinks is to better dissipate that heat build-up to the outside(PC case, then exhausted). While you can increase voltages, those are only done where it meets a happy medium the system can support. Once outside of those tolerances then either better cooling and/or overall quality of ram comes into play. Its pretty much like a race car, you can make it go faster but can you make the tires better to handle the curves, otherwise going faster isn't helping when you leave the track. The same result if you have lousy brakes that can't control the speeds reached.
I am a little bit confused about RAM temperatures. I have been looking at other threads and it seems as if RAM temperatures do not matter. If this is true, why can't I just use ridiculous voltages and overclock my RAM like crazy? And why do RAM coolers exist? If RAM temp does matter, then what temps are safe and how do I know if I am reaching unsafe temps?