If it's 32 chips in total, I remember motherboards having issues with such memory modules since forever basically.
I did try to use a couple 64MB FPM SIMMs which have 2 rows of chips per side instead of 1 and it tended to be unstable until I switched these modules for regular ones.

Could your modules possibly be server memory? (mostly registered modules).

It is labelled PC2 6400U, so should be unbuffered/non-registered.

Anyway the point is that the motherboard manual says the ram won't work due to the chip size [128mb], I really just interested in knowing if there are any DDR2 motherboards that will take it. Is it a chipset limitation for example. The memory controller is built into the CPU [in this case, a Phenom II] so that's not the issue as it's the board that claims not to be compatible.

However googling suggests this is high density ram which is often cheap, but usually incompatible and often slow, so this may be a dead horse there's no point flogging further. I suspect this likely involved an unscrupulous and misleading ebay seller.

Unbuffered/unregistered 4GB DDR2 modules aren't officially supported by any consumer class motherboard that I know of. Some X38/X48 boards have BIOS support for the FB 4GB modules, but those were targeted at workstations. The industry jumped to DDR3 before they would have been commonplace.