hello
i am having a problem with my compaq presario sr1300nx,i installed new memory.went from 256 to 512 and now it wont post or boot,nothing,it comes on,all the fans run,but nothing on the screen,just black,change monitors,still nothing,i get a long beep,about 3 secounds long and thats it,it was working fine before i change the memory ,tried changing back to original mem,still nothing,went through all the steps,pluging and unpluging every thing still nothing-need help asap

A long beep is usually a RAM problem. As you've tried the original RAM, it is possible that there is a common cause fault on both RAM sticks. Like zapped by static electricity. Or not seated proerly (unlikely for 1 long beep).

what kind of memory stick was on your motherboard ddr1 or ddr 2 or sd ram what was the speed if it was a ddr2 533 or ddr 400 and was the memory stick you bought the same at that of the motherboard and was it supported by the motherboard