I'll second the problems with ram pulled from old servers, I added the 4GB from my dell PE2950 to mine and it caused a few hangs once the system had been on for 10 - 12 hours. But since i was setting it up as a server i just ramped the fan speed up and called it done. when it was in testing i had them set at a minimum of 1700RPM, now it is installed as my server (so it is out of earshot) i just ramped it all the way up to 2900RPM. The fans are actually quite quiet when ramped up a bit, so if you are having stability problems i would ramp them up to 1000 - 1200 RPM and see if it makes a difference