Asus P5B Deluxe Wifi + Buffalo Firestix 2GB

[ahmurat]

I installed two sticks of 1GB, the famous buffalo PC2-6400 modules from newegg, but my motherboard recognizes 1GB total memory. I don't know where to begin, can someone experienced tell me what the possibilities are so I can try this evening?
Thank you very much.

 

[ahmurat]

Update...
When I try only one module, system does not boot. I installed the modules in every combination. I always get 1GB total. Do I have 2 x 512 stix indeed? how do i tell? i couldnt find it on the motherboard bios options