If it would help, I could spin up a 9207 card with a Samsung 830 128GB on Win2008R2 and see if I can replicate the issue. Let me know if that would be useful to you or not.
Just tried AS SSD after installing .NET framework 3.5. Same result on the Samsung 830 and 840 Pro. 2.2MB/s 4K writes.
Also... I tried a Vertex 1 128GB. 12MB/s 4K writes on the LSI controller. Wonder if it is something Samsung related?