Is pqi ddr pc 400 not compatible with my nforce-3a board?

[mudspit]

Hi all, hope someone can help me with this, my motherboard nforce3-a have 1 512mb pqi ddr pc 400, when i tried to add another pqi ddr my board didnt detect it, (I also tested each, each memory works fine just but doesnt work when placed both) was is not compatible? and is there any way i can make it work? thanks very much in advance, much appreciate for you help

[edwin]

Email ECS tech support. According to their website, this board should have no trouble recognizing two 512MB modules.