There is a driver for intel ICH chipsets and it was supposed to support TRIM in RAID but it turns out it only supports TRIM on non-raided volumes even though RAID is set in the BIOS. It's here
http://downloadcenter.intel.com/detail_desc.aspx?agr=N&ProductID=&DwnldID=15251
Here is the updated information from Intel
Intel® Rapid Storage Technology (Intel® RST)
Is there TRIM support for RAID configurations?
Intel® Rapid Storage Technology 9.6 supports TRIM in AHCI mode and in RAID mode for drives that are not part of a RAID volume.
A defect was filed to correct the information in the Help file that states that TRIM is supported on RAID volumes.
This applies to:
Intel® Rapid Storage Technology (Intel® RST)
Kind of a good news bad news situation. At least they are working on it.