You either have a bad stick or just not getting it seated well. Tey them one at a time and see if each one will show 256. Also, could be the memory socket so test each one one at a time in each slot.

After a little bit of experimenting I was able to determine that the problem is with the DIMM A slot . . . When I tried to start the computer with a single memory stick in the DIMM A slot, the computer wouldn't come up.

 

I read through a couple of other posts relating to memory and I came across one that suggested that the stick might not be seated all the way. I left the memory cover off and put a little pressure on the stick while starting the computer and it came up. I did as they suggested in the other post, and placed a small roll of paper between the cover and the memory stick, creating a little pressure on the stick, and have it working for now and once again have all my available memory.

 

As mentioned in the other post . . . if someone has a better solution I'd like to hear it.

 

TIA

 

Mitchps