memmory or Mobo?

Hey guys, I have a ecs k7s5a with 512 mb ddr ram. About a week ago i noticed that the coany mputer would only detect 256mb ram instead of 512. i finally had time to check it out last night, i took out both rams and reinserted them, it still didnt work. Then i just put one in one slot first then the other to see if it was that chip or the board that was broken, still nothing. I assumed it was that chip that was broken but when i puit the other chip in the computer still didnt load at all. the moniter has no signal coming to it. Im hoping its the memmory that conked out, its really cheap no-name ddr memmory. But wouldnt the bios still appear on the screen? any comments appreciated, thanks.

Let me make sure I understand. You have 2 sticks. When both are in the computer runs, but only sees one stick. Where are you checking? BIOS? Windows?
When you have one stick in slot one, it will not boot. When you have the other stick in slot one it also will not boot.
What happens if you stick one in the other slot?
Do you have a friend nearby that would let you put your memory in their computer to test it?

not quite, its not working at all now. i had 2 sticks of 256 ddr. i already tried mixing up which sticks go in which slots, but it doesnt work at all. the computer wont post. i wont be able to get ram until this weekend.