P67A-UD4-B3 (rev1.1 printed on board)
i7-2600k
OCZ Reaper 4GB DDR3-1600 (PC3-12800) CL7 (Mfr part # OCZ3RPR1600ULV4)
OCZ 120GB AGIL 3 SATA3 SSD (Mfr part # AGT3-25SAT3-120)
Thermaltake TR2 RX750W PSU (Mfr part # TRX-750M)
Zotac GTX570 1280MB (Mfr part # ZT-50201-10P)
Installed Windows 7 64bit, had the random (only at idle?) freeze issue running stock. No event logs were apparently generated as the system would just freeze. I made sure I had the latest drivers etc, and flashed to the latest bios (official release 3 I think, though 4 is out now).
Anyway I noticed with cpu-z that the ram was running 7-7-7 and at 1066mhz. I went into the bios and manually configured it to run at 1600mhz and 7-8-8 still at 1.5v like it's supposed to run. I haven't had any freezes since, and it's been several days of various benchmarks, gaming sessions, and idle periods.
Just thought I'd share, my issue appears to be fixed.