What size power supply did you buy?
How much memory, what processor, how many hard drives and what other boards are in your system?
Did you get at least a 400Watt power supply?
My PC was great until 3 days ago when my power supply died. Installed a new one and in 2 minutes this one also went out (luckily it has over-voltage protection and hasn't died.) I had to find what was shorting the supply out. After all kinds of testing, I find that everything works fine unless I have either of my DVD drives powered and connected. The power supply goes out whether the DVD drives are connected to IDE1 or IDE2. I pulled out an old CD drive and also tried that on both IDE1 and IDE2. This also caused the power supply to shut down. If the DVD drives are powered but not connected to the bus, everything is still fine (although this means their motors aren't spinning). Again, I can use everything on my PC (all cards and hard drive) but powering and connecting a CD/DVD drive overloads and shuts down the power supply. Anyone have any ideas? I'd really appreciate them.