I just recently installed some new RAM in my HP. i dont remember exact model number im at my class writing this. The problem is when i installed 512 Sdram into the slot it worked fine. so i powered off my PC and put in a 128 Sdram card. When i went to power up the pc i dont get any display from the monitor and the lil green light in the front dont turn on. but the CD rom and DVD drive lights light up and so does the hdd lights flicker for a bit. I dont really know what the problem is also the fans are running. so i took out the 128 ram and it didnt work. then i tried to take out the 512 ram and it still didnt work. im really confused on what to do thanks.