One SSD feels faster than two SSDs in Raid 0 for OS.

Has anyone experienced this? I'm on a Z77 chipset board with ROM 11+ and TRIM enabled (I've checked and TRIM is working) yet Windows 8 feels more sluggish installed in two Samsung 840 SSDs on RAID 0 than in a single one. Even though benchmarks with CrystalDiskMark say differently (the raid 0 array has double the throughput of the single SSD) programs load faster, file explorer moves faster, etc., on the single SSD. What could it possibly be? Is the Raid 0 controller adding overhead of some kind?

It's probably not actually slower, but aside from higher throughput you won't see much difference. I think you set your expectations to see a vast improvement and it just isn't going to happen.

OP, I agree with what's above unless you are doing something very demanding. What sorts or things have you been doing when making your seat of the pants observations?

Nothing really demanding, the whole computer just feels snappier; like opening control panel, files, Visual Studio, etc. The Raid array almost feels like a mechanical drive compared to the single SSD in this respect. When I copy a 10GB+ file over it goes very fast, but when opening a simple program the single SSD does it faster for some reason. Maybe it's just my imagination

Grab a stopwatch and time a whole bunch of tasks. I would be surprised if the RAID setup were much slower...but I would expect that it won't be quantifiably faster either.

And, you could try a different benchmark/performance test. I always liked the Passmark Performance test.