Don't try to upgrade soldered RAM with different density chips.

No. Even if the motherboard supports dual-rank, swapping in higher-density chips on soldered RAM is a fool’s errand.

You’re talking about reworking BGA components — desoldering and resoldering tiny memory chips. That alone is borderline impossible without professional equipment and steady hands. But the bigger problem is the memory controller and BIOS. They’re often locked to a specific chip configuration (density, organization, timing). Dropping in 4Gb chips where 2Gb chips lived won’t just work because the board “supports dual rank.” The controller has no idea what you did and will either refuse to POST or throw memory errors constantly.

Even on upgrade-friendly laptops with socketed RAM, mixing densities can be a gamble. On soldered? It’s a project that will cost you a motherboard.

Buy the right spec from the start. This is not where you save money.