Motherboard : Gigabyte P55-UD3R
CPU : Intel i7-860 @ 2.8GHz
Memory : Super Talent DDR3-2000 (CL9), DDR3-1600 (CL6) @ 1333 CL8 Harddrives attached to Builtin P55 SATA controllers
Random freezes that happen especially on disk access. At time of freeze, mouse moves are possible, Keyboard lights can be toggled on and off, but there is no responsive to mouse clicks and keyboard commands (even Ctrl-Alt-Del).
After a while (usually within 1 minute) the command seems to have played back and everything is running smooth as usual.
Memtest86+: Several full cycles without problem.
HDD SMART: Diagnostics ran with normal results, no bad blocks.
Graphics card: Running 3D games without problem at high resolutions (e.g. World of warcraft @ 2560x1440x32, not that i played it often...)
Event log: No suspicious entry that I can see.
What is the likely cause of such problem?