鞭屍一下......
剛剛由 請問支援PCI插槽的Sata硬碟卡的相容性?這篇延續的討論（感謝lompt的意見），
憑印象上freenas knowledge base找到對於SIL311x的說法
SIL3112 and SIL3114 are “fakeraid”, not really supported in FreeNAS due to lack of FreeBSD software support, however this chipset’s are able to work in FreeNAS in a NON BIOS RAID configuration.
再參考Wiki RAID對於Firmware/driver based RAID ("fake RAID")
的介紹，雖然區隔為soft RAID(by OS)與fake RAID(by firmware/driver)，但意義上fake RAID應當也同屬於soft RAID。
These controllers are described by their manufacturers as RAID controllers, and it is rarely made clear to purchasers that the burden of RAID processing is borne by the host computer's central processing unit, not the RAID controller itself, thus introducing the afore-mentioned CPU overhead.
SIL3124亦為fakeRAID。

給日後查詢NAS RAID卡的朋友留下個參考