I've just attempted, and failed, to upgrade the RAM in my desktop PC, with unpleasant side effects.
I was hoping to upgrade from 512MB to 2.5 GB by adding a new 2GB DIMM into the spare slot on my motherboard. I will say up front that I have had considerable difficulty physically fitting the RAM into the slot and have an impressive groove down the middle of each of my thumbs.
The first time, the PC booted up as normal, but only recognised the 512MB RAM as I hadn't plugged the new RAM in properly. Switched off, started again. Managed to get the 2GB in properly, fine, but when I switched on, nothing happened. No beeps, no display on screen, nothing at all. The drives (DVD R and HDD) both did their spin up, but nothing else. I suspected some sort of conflict between the two RAM chips, so I took the 512 MB chip out and replaced with the 2GB in the first slot.
Again, had a fight to get it in the slot, and I'm not sure I got it in properly - as, during the next boot up attempt, nothing happened. Except I noticed a bright (and I mean BRIGHT) orange light appear from one of the pins of one of the components on the motherboard. I switched off as soon as I could, but not before I started to catch that worrying electrical type smell that says that something's going (or should I say 'gone') wrong.
I've taken the 2GB DIMM out and put the 512MB DIMM back in - seated properly. Now, when I switch on, the CPU fan starts, the DVD R spins up (brief light) and the HDD spins up (quick rattle). The HDD and power lights at the front of the case both show on (the HDD one briefly). There is no display on screen, and the reset and power on/off buttons on the front of the case don't work - they don't switch the PC off. I have to use the switch on the PSU to turn the PC back off.
Help? Have I mangled my motherboard, processor or somesuch? I'm not massively technical, but I'll do my best to answer any follow-up questions.
Thanks very much