zipZoomfly.com just sent me the wrong memory.

Hi, I've just recived my new memory today and installed it and I could'nt get a video signal. The exact message was " No Signal
Analog Signal out
Sleep..."

I didn't know what the heck was going on. I thought my ram was defective. but then I took a closer look at the ram and it turns out Zoomfly sent me the wrong one. I have two ram slots on my motherboard the ram that I already had says
VS512MB400 on the white sticker. The new one zoomfly just sent me says VS512MB400C3. I'm not able to boot up using both chips at the same time but I am able to if I only use one of them. Dose my memory not work because of the different Cas Latency of the new chip? Is the any way I can get both chips to work together?

Go into bios and set the mem timings lower and see if it will run both sticks. Then you should probably run memtest86 to verify that they are error free in your system. This is a good idea just for general maintenance.

The magic 8 ball says, "Dont' count on it"

CAS latencies are not directly to blame, but they are a result of improved manufacturing which probably is. Memory is sensitive and mixing different brands, models etc.. Doesn't always work.

Your best course of action is to send them back and explain they are the wrong modules.

The next thing you can try is to manually set your memory timings. Set them higher (slower) to accomodate the slowest memory in your system. It may or may not work. Your board is probably already doing this automatically through SPD anyway, but at least you can try it before you send them back.