Microcenter iin-store clearance items are on their own table and consist almost solely of customer returns to that particular store -- no multiple items -- and so are one HUGE YMMV.
What I discovered the last time I went to SnootyYuppieSupply is that, at least the St. David's Pa. store quite regularly takes an additional 40% off all clearance items, which makes the so-so clearance prices real . . . and spectacular (Seinfeld reference).
One employee said the sales were intentionally random, another said they were generally on a Saturday and that you could call to confirm first. I spent -- I kid you not -- $1400 smackers the one and only time so far that I encoutered this event.