@ Tiltevros. If you are getting big differences between different benchmarks I would not be so worried. That is more to do with the benchmarks programs than anything else. Try a fresh format as One_Hertz suggested. At least then you can take out degradation from the equation.
I wish I could help but my knowledge is very limited and there are ppl on this forum with considerably more knowledge who I'm sure will help if they can. I tried playing with a raid card and ssd's but I dumped it as soon as I realised that outside of benchmarks it gave me nothing in return. Now I like running a slimed down system. Less to go wrong, much cheaper, less power and no perceivable performance loss.
I don't do any tweaks apart from:
Superftech - disabled.
Defrag - disabled.
System restore - disabled.
File indexing - disabled.