Intel computer crashes on randomly even on idle.

I did pretty much every test to see if it fails but everything passes then later randomly crashes on gaming or idle. So it's really hard to pin point the problem. This the first time I experience this problem and also my first Intel build after coming from AMD. This happen before but I thought I fixed it (lower the overclock to 4.3 GHz). No way heat is issue when it can pass IBT or Furmark. Crashing is like shutdown for few seconds and boots up.
Any idea?

Specs
Intel Core i7 2700k stock 3.5 GHz @ 1.312 vcore
4 x 4GB Samsung DDR3-1600 stocked and slightly overvolt for stability.
Asus P8P67 WS Revolution
6 HDDs and 2 SSDs (RAID-0)
SCMG-3000 SCYTHE "MUGEN 3 " Heat Pipe CPU Cooler with 2 140 mm fans
Two GTX580 no longer overclocked
1000watt Silverstone SST-ST1000-P

The crash on idle issue is often caused when LLC is set too high - what is yours set to?

Oh ok You mean Load-Line Calibration. I been using Load-Line Calibration set on Extreme for months (I had it clocked at 4.3GHz) before this problem started again. I'm going lower it to regular but it's going take a while to see because it's really random. It could be hours or maybe days. Thanks.


---Update
So It looks like it's very stable for 10 days of usage. No crashes and I'm now back with the overclock speed at 4.5 Ghz. Which is great. I been down clocking every time this crash happens and it's finally back. Thanks.

LLC setting is at Regular. Vcore is at 1.325 which is only few settings I mess with.

---Update after few months. It's good at 4.5 Ghz. Thanks.