Help me run this weird memory combo

the mobo is a soyo 7vba for PIII. it has three SDRAM sockets. i have 2x128mb PC133 and 1x256mb PC133. the mobo manual says that i'll never again have problems with memory placement, that i can slap any module in any socket (up to 512mb PC133) and everything will run great. This is what happens:

1x256 = i get 256mb (ok)
1x256 + 1x128 = i get 256mb (WTF)
1x256 + 2x128 = i get 384mb (WTF)

i tried these combos in any and all socket possibilities. when i have one of the WTF combos and run Aida32, for example 1x256 + 2x128, all three modules show in the SPD window with their correct capacities, but still system memory shows as only 384mb. from all this i gather that my 256mb module is only being used as 128mb if i use it with another 128mb module, but this is only theory. anyone can help me with this?

emilio

Onboard video, right? What's the dedicated ram set to? It might just not even be registering that ram with windows and instead directly using it for video.

edit: second point moot

it doesn't have onboard video . . .

Did you update the BIOS? Could be a BIOS issue or something.

It was a guess... no research involved.

i'll try a BIOS update. any other suggestions?