These days it seems to be worse in that sites like the above make reccomendations based on data sheets w/o any actual reviews.
Are there good sources of data or do I just have to assume I might have to buy a few different motherboards, power supplies, etc. till I find parts that work?
If I decide to build my own PC then I start looking up specifications and reviews on individual components. It takes a lot of time but you can eventually find some good YouTube vids or a forum post normally of someone doing an in-depth review of just about everything nowadays. I also don't buy 1st gen bleeding edge releases of any hardware product because I have been burned too many times over the years and it helps save a ton of cash.