Does software RAID 1 in Windows 7 improve read speeds?
I think this blog answers it best. It shows actual speed tests for raid 0 and raid 1 between a single disk, windows software raid, hardware raid, and fake raid.
http://kmwoley.com/blog/?p=429
UPDATE: A more recent forum had a post from someone who tested Windows software RAID showing that the read speed was much faster, but the write speed was slower. If that is true then Windows software RAID is utilizing both disks independently. I have not verified these results myself. See the posting by ColgateJr near the bottom:
http://www.tomshardware.com/forum/250390-32-does-raid-increase-read-speed
Just tested, 2-120GB SSD on windows 10.
RAID 0 increased both read and write dramatically (non-raid read was 450MB/s, raid-0 read was 820MB/s). Raid 1, write speed is the same, read speed increased by almost half (non-raid read was 450MB/s, raid-1 read was 631MB/s).
Side Note: I know were're talking about raid-1, but for someone who's speed hungry and want raid-0, just remember that if something slightly goes wrong with one of the drives, your system is done (crashes). Consider a raid-5 setup if you want both speed and redundancy.