DDR RAM is designed to be backwards compatible, so you can install the PC2700 RAM into your PC2100 computer without issues. Just note that it will run at PC2100 speed unless your motherboard is capable of handling PC2700 RAM. If the PC2700 stick works correctly, the old stick is most likely shot. (I find it unlikely simply removing the stick would end its existance, but it is possible.) If it doesn't work, though, your motherboard and/or processor may have finally bit the dust. (With onboard components previously fried, the chances are very good that the motherboard has/will die(d) from the after effects of the blast combined with continued usage.)
You pretty much covered all of the bases, but my lone question would be how you 'cleaned' the RAM. You should always play with such in a static-free environment, meaning you should ground yourself, watch what material you use to 'clean' it with, etc. If you didn't, it is possible you electrocuted the RAM. Also, with the other stick sitting in a drawer, it might have also been damaged, depending on how it was stored and what came into contact with it. Just a thought in case the other stick doesn't work either.
Hope this helps,
The quick version first:
I have an HP computer, 2.5 P4 with 1x512 MB PC2100 DDR ram. I have a stick of ram I bought a while ago for a different computer, but it was the wrong type. I thought of it sitting in a drawer, so I pulled my ram out of the PC to compare the two. Not the same. So I reinstalled the original stick and when I turn the PC on, the monitor goes to "standby" mode, ie, it goes black and the power light starts blinking. Did something happen to my ram stick? I've pulled it, cleaned it, reinserted it many times now, trying both slots, but it's not booting. Question, my ram is PC2100 DDR which is I think, 266 MHz. I found a stick of PC2700 DDR that I can install to test to see if my ram is now bad. Would the PC2700 work in my PC? I've heard that PC2700 is backwards compatible with PC2100.
The details. The computer was hit by a power surge about a year ago (I'm not original owner). It was given to me in non-working order. I found the onboard sound and modem to be fried. I disabled both in bios and replaced. I've been running the PC for a year now. I upgraded it from onboard graphics to a cheap pci Radeon 9250. I'm wondering if the ram could have been ready to go bad and pulling it was what it took for it to break. In diagnosing, I pulled all cards from the PC and installed to test in the old PC. All worked. I installed the harddrive in the old PC and it works. I also swapped monitors to eliminate the thought that the signal cable was bad. My other monitor did the same thing when connected and I tried to boot. I am also sure that the memory stick was not installed backwards. That really leaves me with the memory stick or something on the motherboard. I'd like to know if I swapped the memory for something that does work would allow me to boot so I was sure my memory was bad. But the only memory I have available was PC2700, like I said. Should the PC2700 work?
Thanks in advanced for the help.