kernel:[193562.569274] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: RES (no timeout)

Since upgrading to fc17 been getting: [192963.306958] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: SRC (no timeout) [193262.911077] [Hardware Error]: CPU:4 MC4_STATUS[Over|CE|MiscV|-|AddrV|CECC]: 0xdc20c000dd080813 [193262.916531] [Hardware Error]: MC4_ADDR: 0x000000081f2e2020 [193262.921903] [Hardware Error]: Northbridge Error (node 1): DRAM ECC error detected on the NB. [193262.927322] EDAC amd64 MC1: CE ERROR_ADDRESS= 0x81f2e2020 [193262.932657] EDAC MC1: CE page 0x81f2e2, offset 0x20, grain 0, syndrome 0xdd41, row 3, channel 1, label "": amd64_edac [193262.938047] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: SRC (no timeout) [193562.542225] [Hardware Error]: CPU:4 MC4_STATUS[Over|CE|MiscV|-|AddrV|CECC]: 0xdc61c000bb080a13 [193562.547766] [Hardware Error]: MC4_ADDR: 0x000000081f2f1370 [193562.553153] [Hardware Error]: Northbridge Error (node 1): DRAM ECC error detected on the NB. [193562.558564] EDAC amd64 MC1: CE ERROR_ADDRESS= 0x81f2f1370 [193562.563895] EDAC MC1: CE page 0x81f2f1, offset 0x370, grain 0, syndrome 0xbbc3, row 3, channel 1, label "": amd64_edac [193562.569274] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: RES (no timeout) Could be a real h/w problem or related to the upgrade? Advise welcomed...Any kernel boot switches that may help. Seem to run for a while just fine, then start periodically getting these messages. Have not run memtest+ yet, plan to shortly, but sound like L3 cache, would this show up in memtest? Thanks for advise!