Well, you have a great start.
As always, I like mailpup'ss suggestions.
There are so many things to check... bad memory module or bad power supply being the most obvious, but grounding issues, cable issues, electrical issues connecting to the wall... bad CPU, bad CPU fan, too much CPU thermal paste rather than too little.
I would start with trading out the power supply with another, then the most simple possible connection... motherboard, CPU with thin thermal paste, one memory module, new or different CD or DVD player, and try booting to a simple Windows disk... If it works, change a component... keep on going, keep on changing, test every combination in simplicity, and once those all check out, start over with more complex setups...
You may have to do all this to track it down... But distrust the power supply it can make all the noises of one that is working, but can still be totally shot... then distrust the memory... any one module is enough to test... Keep changing those modules around.