Just keeping this GTX680 hardware talk out of KGB thread :D
Yep, sounded like that's could have been what was happening. I tested and my mem at stock (+0 mv) is 1.59v. Not sure if this is the same with all lightnings - can someone comment on that? I have tried 3 now and they all hit over +700 mem stock.
My last card is the best though, +750 BF3/everything stable, I will do some comparisons to show what it's gaining over stock & the common 7GHz mem freq. Probably going to be more in games where mem is loaded hard like Crysis.
Just an update where I'm at. I took my problematic 1st card back (came with a locked F8 bios on LN2 mode that artifacted badly in 2D mode - had to flash 3A onto it myself to fix it) and swapped it out with another. It was better, managed 1241/+700 core game stable stock and with bios unlocked with KGB giving 1.24v load was 1267/+700 heaven/BF3 stable. I considered my options then picked up a second lightning, this one is a keeper. 1280/+750 heaven/BF3 stable and very close to 1293 stable at same voltage. When my water block arrives I'm pretty sure it will do 1293/+750 rock solid @ 1.24v. Temps now are at ~63*C core/~65*C mem/67*C vrm loaded with ~30degC ambient summer temp and that was with 65% fan (loud!). Testing this card on air reminded me why I watercool. That said with 2 nice examples here it's tempting to just throw them both in SLI and run them stock with brutal FPS in everything :D