I bought a new CPU. I still want to use the other one for different things. I am using the same monitor with the new CPU that I used with the older CPU. I got a monitor from a friend (Yes, it works, I saw it before I got it). When I turn on the monitor to the old computer, it says "no signal" and goes blank. I put the other monitor back on it, and it works as it always does did. I put the friend's monitor back on and it says "no Signal". I have tried 3 other working monitors on the old CPU and they all say "no signal", except the monitor I used to use on it, which is now hooked up to the new CPU. What's the problem???