This is 99% sure to be failed memory. The 2nd line of your log is pointing to a memory error on DIMM 3, and later the CPU causes a panic to crash the box due to this unrecoverable memory error.

Latest versions of Sol 8 kernel patches had better error correction routines, but if it truly is failing memory that's not going to help much. I'd say replace the bad DIMM, or if the box has enough you can just remove the bad memory and keep it running on less try that and see if it helps.