Stick to AHCI and NO RAId. I tried RAID on my two 1 TB Samsung 840 EVOs, yeah good benchmarks, but usage wise, you will not notice on bit of a difference, only the added hassle in updating firmware and managing your drive:
[h=1]Samsung 840 Evo 1TB RAID vs. RAPID Benchmarks[/h]
So here are benchmarks of my two 1 TB Samsung 840 EVO SSDs, both in RAID 0 and in RAPID. The 4K speeds are horrible in RAID 0
AS SSD Benchmark with IRST 12.9.0.1001 in RAID 0 (W8.1)
AS SSD Benchmark with IRST 12.8.0.1016 in RAID 0 (W8.1)
Not very happy to be honest. those 4K speeds are horrible
Previous benchmarks with RAPID, 4K is way better:
AS SSD Benchmark with IRST 12.9.0.1001 (W8.1):
AS SSD Benchmark with IRST 12.8.0.1016 (W8.1)
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Windows 7 Benchmarks:
AS SSD Benchmark with Intel Chipset Drivers 9.4.0.1027 (W7) [RAPID]
AS SSD Benchmark with IRST 12.0.7.1002 (W7) [RAPID]