Thank you for your replies.
Yes, I am aware the late 2009 iMac has SATA II (which means 3Gb/s). But what I am asking is this:
Does the late 2009 iMac have DUAL CHANNEL SATA II?
In other words, is there a SATA II 3Gb/s channel for the internal HDD AND a separate 3Gb/s channel for the Optical Drive?
Why do I even ask this question? Because if the late 2009 iMac is only a SINGLE CHANNEL SATA II machine, then putting an SSD in the internal HDD slot and another SSD in the optical slot will NOT give you more throughput, seeing both slots share the same slow 3Gb/s SATA II channel.
HOWEVER, if the late 2009 iMac is indeed 2-channel SATA II, then in theory, putting 1 SSD in the HDD slot and a 2nd SSD in the optical slot would yield 3Gb/s + 3Gb/s = 6Gb/s speeds.
And so, since you apparently are putting two 1TB SSDs in a late 2009 iMac and putting them in a RAID 0 config, what are your Back Magic Speed Test results?
https://itunes.apple.com/us/app/blackmagic-disk-speed-test/id425264550
If you only get about 275GB/s to about 290GB/s speeds in the Black Magic app, then you are only getting SATA II 3Gb/s, and that would prove the late 2009 iMac has only a SINGLE CHANNEL SATA II line. But if you get something like 500GB/s in the speed test, then it proves that iMac is DUAL CHANNEL SATA II.
So you can please run the Black Magic speed test and post your results?
Thank you.