<<
This is why there are "tiers" of manufacturers. Regardless, most thought in this area is anecdotal. Read the forums here and on OC Workbench, and then honestly see what seems to have a higher rate of defective motherboards: The Asus A7V266-E or the ECS K7S5A? >>
It is hard to interpret anecdotal evidence; that's why we set up this poll on anandtech:
K7S5A + AK31A life/death stats
...you can go to the threads, where the polls have subsequently collected more votes, pushing results slightly more in the K7S5A's favor (do a search on "life/death" from this forum).
To quantify your speculation, we need the analogous poll for the asus A7V266-E. The prior polls showed us that both the K7S5A and AK31A had problems, particularly with DOA and early death. It is hard to determine how many of those problems result from ESD and retailer recycling.
The stats at ocworkbench are rather remarkable -- 40 times as many ECS posts as posts for any other manufacturer. However, that site has become known as an ECS knowledgebase, and offers more for ECS users, than, say, asus users (OC BIOS, faqs, etc.). The bulk of the ECS posts are actually along the lines of, "have you tried this? what temps are you getting?"
Do a search on A7V266 in this forum -- I notice quite a few threads reporting systems that won't boot, and one thread entitled "Asus A7V266-E & KT266A - in short, it's crap!".
By the way -- I've owned 3 asus boards -- K7V, CUSL2 and P4T-E. For me, they have been largely trouble-free, but each has had a bizarre and annoying quirk. Were it not for help from forums like this one, those quirks would have had serious consequences. The problems turned out to be well-known, and had solutions documented on the web; but the solutions were
not documented on the asus web site. My latest is a P4T-E, which can be very fussy about mice. If you track the asus USENET posts, you'll discover that the mouse/keyboard problem -- which cripples the system until the user gets the correct magic formula-- is a common "issue" with this board. So even first-tier manufacturers fall down from time to time.