Ya Mx I was wondering if it's degredation myself. But maybe you're right and it was never really all that stable. But it wasn't this unstable prior and it has just annoyed me at this point. Again thankfully the performance is good, but the OC-ability of this chip has turned out to be much more of a hassle to find than a K chip should be imho. Wish I had money to buy another one and sell this one.
I will say the Asus board has been pretty awesome thus far, I love the bios and featureset.
I'm also thinking that it is more likely that your original settings were not completely stable rather then the chip suffering from degradation. It doesn't sound like you were pushing excessive volts if you were mostly at around ~1.25v set in BIOS.
Like
Womper already mentioned about his chip...
I also have experienced more then my share of "long term" instability with my chip... mostly random BSOD's and sometimes the occasional freeze in my attempts to dial my overclocks. I like to "crunch" Rosetta/WCG so my system pretty much runs 24/7 100% load. I have found Haswell to be more challenging than SB/IB at establishing stable daily "crunching" overclocks but I think I might actually have two that so far seem to be working for me??... One at 46x DDR3-2666C10 and another at 47x DDR3-2133C9.
I would go back and try starting over again testing at lower speed overclocks...
Keep your CPU Cache multi on auto (39x) CPU Cache, CPU SA, CPU Digital/Analog I/O voltages all on auto. Run memory at 1600 speed with XMP (defaults/1.6v for your kit/F3-17000CL11D-8GBSR?).
I would test again for max multi(s) that your chip can run with vcore set in BIOS to ~1.200v/1.225v/1.250v. So maybe something like... 42x@1.2v, 43x@1.225v and 44x@1.25v.
Mine seems random and inconsistent. But it's probably just me being a noob.
Anybody using Samsung Green with Haswell?
I don't have the low profile Samsung Green kit but I do have several kits that use similar ic as the Green... (Samsung rev. D). I have some GSkill Trident X sticks that should be using the exact same HYK0 ic as what is used on the Samsung Green. They have run well for me up through 2133C9/2400C9 speeds. My kits can run higher speeds but they are also a higher bin... 2600C10/2666C10. Benching higher speeds with Samsung on Haswell may also require making adjustments to Secondary/Tertiary timings and RTL's in the Memory section of your BIOS.