Ask the Doctor: Whither the RAM?


I have two 256MB RAM modules. I recently bought an additional 1GB DIMM. A friend of mine asked me to try his RAM, as it was the same as mine. I tried it and my computer flashed an error. I stopped immediately, removed my friend’s RAM, and shut off my computer. The 1GB DIMM was installed and so were the other two 256MB sticks. But now the computer only recognizes the 1GB and says the other slots are empty, despite the presence of the 256MB DIMMS. How can I get the system to recognize the rest of the RAM?

—Tom Hensley

So, to sum up, you had two 256MB DIMMs. You added a single 1GB DIMM and it worked fine. You then added your friend’s DIMM, POSTed the machine, and received an error. Now it no longer shows anything but the 1GB of RAM?

Lesson number one when swapping RAM, or anything inside your machine, is to power down the machine by either unplugging it or flipping the power switch on the PSU itself, and then pressing the power button to discharge the remaining power in the PSU’s capacitors or waiting five minutes before mucking around.

What you are describing is not good. It sounds like you may not have fully seated the DIMMs or seated them so that you actually shorted something when you powered up the box. If you’re lucky, there’s just something in the slot like a huge dust bunny. With the power completely off, try reseating the RAM and make sure you have the orientation correct. Yeah, the Doctor knows the RAM is keyed, but you can actually jam a DIMM in there far enough that you think it’s installed even though it’s backwards.

If the memory still does not show up, completely shut down the box, remove the 1GB DIMM, and install each of the 256MB DIMMs in the slot the 1GB was in. If the PC now recognizes the 256MB DIMMs in that slot, you likely have two bad slots—highly unlikely. If it does not, you likely have bad DIMMs—also improbable. We think your troubles will be fixed before then with a careful reseating.

SUBMIT YOUR QUESTION Are flames shooting out of the back of your rig? First, grab a fire extinguisher and douse the flames. Once the pyrotechnic display has fizzled, email the doctor at for advice on how to solve your technological woes.

Around the web