Honestly, heating in an oven like that is too uncontrolled for my taste. I would rather inspect very carefully and only reflow suspicious joints, using an iron.
Yeah, this is always the best way. I also use a heat gun with a good set of adapters to help concentrate where I know might have a cold solder joint fail.
But in cases such as a motherboard failure, I usually just cook.
Like I wrote before, most tech savy ppl cringe at what I link to sometimes, but hey, look at what they do in third world countries with less than a third of resources even I have on hand, and when they swamped with the mass junk we send them, they make the most wonderful educational videos I have ever seen.
I was learning one of the new MIT free online courses, on robotics. But found myself learning more from some videos in war ridden countries where necessity is a daily thing, or in india where you see some dude just going ballistic, re-balling, eye balling, yanking surface mounts at frenetic speed and actually what seems to me, also learning as he wonders through a field of broken pcbs which are polluting his land fills that WE send to them cuz WE are to lazy to fix them.
I was homeless for awhile, washing up in subway stations on the sneak in TO. So I know a bit about survival, then when I went to work up north, THE REAL north, man oh man, did I learn there also about differences in community, and how we can work together.
I have not posted for a while whilst impaired, I do like my beer and smokes, but lately, I am more less inclined to indulge because this is the first time I have ever seen such a dilemma, and helping others makes more sense to me. Giving them options such as cooking a board at 250 for 10 min stints. I set mine to 250 probably cuz the darn toaster is so old it probably only attains 200.

This is NOT a science. Its guessing at this point.
Yes, all toaster ovens differ, this method is very dubious at the very least for the educated, but hey, it works, some times. And that is all you can hope from last ditch or as billr so aptly wrote, hail mary. I agree on all points here and should have huge red disclaimers everywhere about how nefarious the vapors can be, or how this stuff may pollute our water supply, but at the end of the day, we are still stuck with broken stuff no one wants to fix and roll of a cliff.
Now, is the best time to try last ditch efforts, such as listening to mother nature and pondering how we as a society can do better.
Ok, my mary poppins act is over, I just felt compelled to write something positive for all.
In my life, I have only joined in serious fashion, 4 sites and have fun with, camaderie and all.
My first one was homeless in TO. I published there a few times. It was a cool adventure. Second one was right here, after coming back from the living dead.
Third one was and is a pc learning site, 4th an overclocking site.
All these made me learn immensely, through the wisdom of folks like jack, bill the other nick, dan, dabunk, jim, and others who I crapped on, didnt give up on me when I understood nothing cuz my french english was sounding like dolly parton in the ears of a china man.
I am a true atheist, but I do believe in the power of helping. Karma is my bitch.