There are two sources that may answer your ?, either the chipset(RAID) being used or the SSD maker. The specs and tech sheet should offer what can be done. Understand, while RAID is being done that's an extra step in the process. Once TRIM is added, it is yet another step involved, which will degrade performance sooner or later when actually used together if at all.
TRIM is provided by the OS to help maintain the data storage R/W operations and RAID is used to spread the load of data in some way to keep data safe. Different wording maybe used to describe what I've said, but overall that's about it. In other words, it becomes complicated as data gets handled. There maybe ssd provided s/w that involves what certain features are active/in-active so that's open. While TRIM is OS domain, that too maybe controlled outside of the OS if again ssd s/w does that or not. If performance based, it sacrifice some feature in order to maintain high levels of performance, rather that's good or bad depends on the use and/or what the data is required as in more permanent storage or back-up or gaming, etc.. Check ssd user manual as well.
Read in several places that you lose the trim functionality on an SSD drive if it is part of a raid setup.
Is that still true if using a new Samsung 840 pro SSD drive and windows 7 professional?
In other words is this old outdated information on the web or is it still true?