Tyan Thunder board memory question

Guys can anyone please advise. I've got a S2895 K8WE board and am having difficulties in adding additional ram. It is running fine with all slots filled with 1G modules apart from CPU1 slot B2 and CPU1 slot B1 which have 2G modules installed. I'm now trying to add 2 additional 2G modules into CPU B1 and B2 but the computer blue screens.

Can someone please advise me which slots I should add this additional memory into as the manual does not help but perhaps I'm being a bit dim.

Many thanks for your assistance.