|The Dell Dimension 2400 orginally comes with either a 200 or 250 watt power supply. If you didn't swap PSs that may not be enough capacity for the 3000's mboard. |
Ram modules that work in the 2400's mboard won't necessrily work in the 3000's mboard. In the worst cases of incompatibilty, the mboard will not boot, and there are no mboard beeps. Did you use the ram modules that were in the 3000's mboard originally in the 3000's mboard ?
In addition to that, I know from experience, the 3000's mboard is more partcular about which ram modules work properly in it.