|First off, this has nothing to do with the first poster's problem. He was talking about a USB memory fob - aka, a thumb drive, flash drive, etc. etc.|
Second - very unlikely that more than one or two people will see your question here. You should start a new post.
Third - since you asked, what does "my Motherboard seems to not react to them" mean? Does the computer boot since you added the new memory? If it does, the motherboard most certainly does "react" to the new memory. Normal behavior with no memory in the slots would be for the computer to beep several times when you power it on, and not display anything on the monitor. Is that what it's doing? If not, you need to describe what is happening in much more detail.
Take care to describe what is happening and not your interpretation of what is happening. What do I mean by that? Well - saying that the computer "acts like there isnt anything in the slots" is your interpretation of what is happening because it implies that a specific behavior should occur when there is something in the slots, and that this behavior is not occuring. This is a bad way to describe what is happening because....well, because it doesn't decribe what is happening. All it says that what you assume should be happening, isn't. But you don't tell us what you think should be happening. All that you have really told us is "my computer isn't doing what I expect it to". Not helpful, and not likely to get your question answered in any useful fashion.
A better way to ask for help is to describe, in objective terms, what is actually occuring. For example, you could say "when I turn the computer on it does X for a while, but then Y happens. It never does Z, which it used to before I installed the new memory. Is this normal?". Now, we know exactly what is happening and what you expected to happen. See the difference?
So, short version - describe in as much detail as possible what actually happens when you turn the computer on. And do it in a new post, for maximum exposure to people who can help you.