Motherboard or Memory causing problems?

These past few days made me pull out more hair then ever. I had 256 MB of pc2100 DDR Micron memory, then i droped a Harddrive on it, while it was out of the computer, knocking off a resistor, so I went to the local computer store and got 2 sticks of Infeneon pc2100, popped them in and i was running smoothly with 512 MB. Then I restarted my computer and i got these long beeps , and my comp would not post. So I played around with the modules and came to a comclusion that one of the sticks was defective or something. When I went to eturn it the guy tested it and said that it was fine, so i asked for a diffirent brand, and i got Micron pc2100. I bring that home, pop it in and it boots up fine, except at the memory check it says that i have 256mb. Now Im worried tha my mobo is defective, since i only used 1 slot up until now. Now I don't know what to do. Someone help please, i spent hours playing around with it and no positive results.

Sounds like either the contacts in the memory slot are corroded or weak so they are not making good contact.

I would use a q-tip and rub the contacts in the slots and look for a contact pin out of aligmnent.

You can also try using one stick in each slot to try figure out what slot is giving you the problem and if you have three or four slots just don't use the bad one.

I tried all hat, i even went through the two dimm slots with a really small screwdriver pushing all the little connections out a tiny bit further. nothing happened