Computer on but nothing on monitor??

My computer was working fine an hour ago ... i turned it off to put in a dvd recorder / lightscribe, a 4 port usb card and 2 1gb ram sticks. I lost my dad last month ( he was my computer expert ) and brought home a bunche of his computer stuff. I also removed the ?CPU? chip or the ?processor? chip (the one under the fan) to see which one it was and to see if he had a higher grade one (which he didn't) so i replaced it exactly the way it was. Put everything back together turned it on and nothing shows on my monitor... light is amber blinking... i unpluged the monitor from the computer and the no connection, check signal cable box comes up.... so it's not my monitor. Also there are no beeps when i boot up my computer. All fans run also. Just nothing at all showing on monitor. Please help! I have tried messing with the video card resetting it and the ram sticks and nothing. Also re input the 2 ram sticks that was previously in there and nothing. WTH did i do?

 

ok i just did the video card again without putting the screw in and turned on the computer and it beeped..........then a min later beeped again......but still nothing on monitor???

 

Nevermind Lol

ok nevermind about the nothing on screen :| dunno how but its working now... in system... it says 1.5gb ram at 1.40 ghz but i believe it was 2 1gb ram sticks... why it only shows 1.5 ram?