Yep, lots of combinations were tried. 2 different 2500ks, a 2400 and 2600k. We simply can't duplicate the problem. The only explanations I can come up with if anyone does suffer the problem is;

1. Your OC may be unstable somewhere, even if stability tests don't pick up any problems. Safest thing is to try sleep at stock settings, if all is well, probably something wrong with the OC.
2. Early 1155 CPUs (D1s I think) didn't support internal PLL. So if you can't wake from sleep it's probably where your CPU is a D1.