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Unless you injected (F6) or other method the Intel RSTE driver to Windows 7 during OS installation then changing the Intel SATA -> RAID will result in a BSOD - guaranteed. See my Guide - http://www.tomshardware.com/forum/303873-30-wont-resume-sleep-booted-raid#t2068879
Only the Intel SATA ports offer full bandwidth to the SATA ports. In contrast the ASMedia ASM1061 is PCIe 2.0 x1 or 500MB/s over (2) ports max - http://www.asmedia.com.tw/eng/e_show_products.php?cate_index=117&item=118
vs Intel SATA2 (600MB/s 2 ports) or SATA3 (1200MB/s 2 ports). File structure is the limiting factor to seq/random R/W speeds.
My preference is always the Intel chipset SATA when/if not using a Dedicated RAID Card.