I am working on a Compaq Presario SR5510F and it would not boot up. Sometimes it it boot further than at other times. I open up the case and took out the second 1GB stick and it booted up. So I was thinking the RAM in the second bank was bad. I ordered an upgrade of 2-2GB PC2-6400 and put them in and the PC will not boot. I took out the second stick and it boots up. So it seems to me the second bank on the motherboard is bad. Any suggestions on what to do now. Replace motherboard? Trash the PC after I have backed up the data? Or just let it alone and let it have the one 2GB stick? One other thing I could do is do a system recovery and put the system back to the original factory settings and see if it will recognize the second bank after that knowing I will lose all programs installed on this PC since it was first bought.