Wha? RAM has used BGA since DDR2 and even before. It's been part of the official specs since DDR2. No wave soldering there.
It's a pain but my advice would be first try a minimal hardware config with the existing Windows install. If that's of no help do the minimal config on the "dummy" Windows install.
It depernds which manufacturers perhaps Ry, I've seen the Corsair RAM production line, they, or at least used to, wave soldered after chip insertion from the underside of their boards, perhaps that is why they are so reliable :)
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