The lower-quality chip has higher leakage, and as such either it cannot handle the higher voltage because A: the leakage is too high, or B: the current draw at the higher voltages, because of that leakage, is hitting over-current limits. So, why is ASIC quality important? Well, it's important in different ways, depending on what you want to do with the card... For most users, the higher the ASIC quality, the better, and this will result in the most efficient chip at stock, but these same cards amy not clock very high. For extreme users, they want low ASIC quality, as higher leakage tends to mean that when frozen and that leakage is dealt with, the card will perform better, and is less likely to coldbug, than a card with higher ASIC quality. I try to monitor the data people are listing for ASIC quality, and i think that over time we'll be able to suss out which cards are best for which users, whether air, water, or extreme cooling methods are used, based oj specific ASIC quality ranges. Each user will want to look for cards within a pre-spoecfiied range to get the best 24/7 results. Your own testing here confirms my own findings about silicon and leakage, and how those relate to clocking, so it's interesting to me that you seem to confirm the same thing. This is relatively a new addition to GPU-Z, but has been something I've personally been paying attention to for years. Many people have asked me why i think high-leakage parts are good ,as to an electrical engineer, this is not the case, as they look for the greatest EFFICIENCY, which may or may not relate to how the chip behaves at high frequencies and extreme cold.