The ICH10R basically just supplies the SATA ports, it's the chipset drivers (i.e., the software) that's loaded into the operating system that does most of the actual legwork for RAID sets. The biggest significance of the chipset itself in RAID terms is that it contains the BIOS code to create and store the configuration information, as well as providing boot support for an OS on various RAID organizations. This means that, unlike many other software RAID solutions, you're assured of being able to boot from a redundant RAID set (ie RAID 1, 0+1 or 5) that has a failed drive.
So yes, the ICH10R chipset does require CPU cycles in order to run the RAID set. But for RAID 0 and RAID 1 the overhead is so low as to be negligible. RAID 5 requires a little more CPU power because of the need to handle parity calculations, but even so on modern CPUs it's unlikely to use more than just a few percent of the CPU even at very high I/O rates. In fact I'd guess that the RAID CPU overhead is less than the work done in the file system itself to track metadata such as where the file blocks are physically located.