Hi, my mom has a Dell Dimension 4550 that has been running fairly smooth for several years. Recently she tried to install some new DDR ram in to the mobo, and VERY incorrectly seated it. She asked me to look at it (after the fact) cause her computer would power up, but not load bios. Turns out she had the ram in upside down, so naturally because of the notch it didn't go in right at all. I seated the ram properly and tried to turn it on, same thing. I even removed the new piece of ram, leaving the original 512, and it still won't boot. Any tests I can run to see if the mobo is fried? any suggestions I would appreciate. Thanks!

I think you have accidentally touched or moved the old stick. Pull it out and put it back. Maybe it was not properly seated in the slot.

thanks for the quick response. I reseated the old ram, still nothin, tried it in the other slot, nothin. I also tried just the new memory in both slots, nothin.

I probably should add that the motherboard doesn't give any beep codes, and that, as far as I can tell, is not a good sign

Meanwhile, look for the diagnostic lights found at the back of the cpu case. Observe them.

Then, pull the video card and a memory stick out of the motherboard and seat them again in their slots. Leave the cmos battery out for an hour then put it back again. Start your computer.

well, my mom took the computer to best buy, and they ran some tests and found out that putting the ram in backwards probably caused an electrical arc, effectively killing the mobo. Thanks for your help anyway!

Okay, your computer is running fine again. Good luck.

my dell dimension 4550 wont load windows and i dont have any disk.

I have a Dell Demension 4550 that was given to me. when I turn it on it goes to press F1 to reboot or F2 for set up. It shows primary drive o unkown device & primary drive 1 unknown device & the secondary drive o cd rom reader & secondary drive 1 cd rom reader & can't get of the bios to get to the internet. Can you help me??