My pc will not let me upgrade ram past 1 gig

[mesogreat]

I try to upgrade past 1 gig and one of two things happen. If I fill up all slots with 512 sticks for 2 gig the pc continues to crash to bios entry screen. If I put in 3 512 it only reads 512 ram. If I put in two 512 sticks it reads fine .

System specs a8mvp crossfire 1900 corsair 3200xl 2-2-2-5 ram windows xp fx-53 500psu enermax

 

[(cf)Eclipse]

bump vdimm up to 2.7v for all 4 sticks?
command rate is set to 2T, right?

 

[mesogreat]

I bumbed vdimm to 2.7 but it kept going to bios to reset default. Where would I find the command rate to see if it is set to 2t and not 1. My abit bios showed that easy but can/t seem to find the place where it is in asus bios screen.

 

[mesogreat]

bump

 

[davef139]

Find your motherboard manual some mobos (older ones) will only allow upgrading of ram in pairs, and must be inserted in particular ways.

 

[TheGamerZ]

Find your motherboard manual some mobos (older ones) will only allow upgrading of ram in pairs, and must be inserted in particular ways.

I don't really thing his a8mvp crossfire 1900 board is that old

 

[mesogreat]

Yeah looked in the manual and still can't find anything about cammand rate settings.. I wanted to check on that as someone had mentioned. Anyone else out there with this board know where it's located in the settings.