I wouldn't trust any tool to tell you what your maximum is, there's no way for the tool to reliably know this. You need to identify your motherboard model with something like
speccy, then do some googling to find the true limit.
Don't necessarily assume that the manual for the motherboard is correct, often this is down to higher-capacity modules not being available when the motherboard was released, so they can't claim it supports higher capacities because it was never tested. You get the same thing on phones with expandable storage, they'll usually say "Supports Micro SDHC up to 64GB or something, but when 128GB or 256GB cards come along, they work just fine.