HP pavilion 7855 RAM issue!

[frummaceuk]

i have an old hp pavilion 7855 and it came with only 128 mb of ram. I decided to upgrade it. It uses pc100 ram so i bought a stick that was supposed to be pc100/pc133 compatible, but it didnt work. Now i have a stick of pc100 only and it still doesnt work. The strange thing is, the computer only recognizes the 128 stick when it is in one of the slots, when it is in the other, the vga output is nonexistant. but when i put the 512 pc100 stick in the "working" slot, it still doesnt give vga output.
help?

 

[cohen]

Ram problem - maybe the mobo won't take that speed of ram.

 

[Quick69GTO]

Go into the BIOS and manually set the front side bus to 100 and the RAM speed to 100.

 

[Gareth]

The maximum RAM on the Pavilion 7855 is 512MB (2x 256MB sticks) which will explain why the 512MB stick wont be recognized.

 

[frummaceuk]

for real?

ok... so what do i do now? will it accept just one 512 stick? and how does that explain why the computer boots up only when the 128 is in a certain slot?

 

[Gareth]

Id return it for 2x 256MB Sticks and try that. Older motherboards are very particular about their memory, and it should be in DIMM A for single stick of memory. I doubt it would accept 1x 512MB Stick, but its worth a shot.