So specifically, the problem here is that the contacts are made by tiny spring connectors on the motherboard. They 'spring' a distance of about 0.2 mm - which

So specifically, the problem here is that the contacts are made by tiny spring connectors on the motherboard. They 'spring' a distance of about 0.2 mm - which accounts for bending or flexing of each board. However, if the screws aren't tight, then perhaps 0.1mm of your 0.2mm range is wasted, and the RAM might work until the motherboard is bent or flexed and then it'll stop working. End result: You have a laptop that crashes whenever you pick it up from the 'wrong' corner.