I'm experiencing frequent system crashes at the moment and I've run out of clues for diagnosing the issue. Crash is a full lock up, display is frozen yet coherent, no response from kbd or mouse. The caps lock light does not flash nor can it be toggled, and SysRq combos do not work. Network is also unavailable. Nothing relevant in logs. Crashes are unpredictable, occurring at idle or under load. Uptime can range from 2 seconds to a week at best. Loading video content seems to be the most reliable way to trigger it though. OS is debian testing. System has previously been stable, and first known crash did not correlate to patching. Principal system components are: AMD FX8350, Asus 990fx Sabertooth MB, Samsung 840 Evo SSD for OS, Corsair RM750 PS Investigations so far: Memory ------- - Memstest86: ran for 24 hours, no faults reported - Problem persists when running on either or both of the compatible DIMMs I have for this board Misc. Drivers/HW ------- - Removed non critical HW: problem persists GFX Cards/Drivers ----------------- No integrated GFX with MB or CPU - Run entry level GFX cards with chipsets from AMD and Nvidia using open drivers for each: problem persists Kernel/OS --------- Configured kdump and can analyse dumps resulting from simulating a crash via 'echo c > /proc/sysrq-trigger' or "Alt-SysRq-c". No output results from the crashes I'm complaining about. Problem persists when booting from live CDs from different distributions. Any suggestions would be appreciated, I don't think I've missed any obvious tests. My next step is to take MB and CPU back to the shop (who thankfully are pretty cool for these type of claims). Cheers, Dave