|A power supply is best purchased by weight. The heavier is usually the better device due to quality components having more weight. Occasionally, technology can reduce weight, but so far this is a good indicator to go by.|
Does this new power supply test good? How about the old one?
The mainboard is a socket 939 Asus A8N-LA. I hope you found it cheap. Those are almost antique. I have two in the "toast" bin. They are bad because the RAM was removed from both (swap) while the unit was still plugged in, but powered down. Son learned on that one. Very touchy boards these days. 5 volts of static / power will toast 'em, and just about everything attached at times.
"When the DVD player is plugged into mobo, it will not work."
Does the dvd work in other systems? I would test in an external USB adapter / case to have something to protect the computer in the event the DVD is bad. It sounds like it may be bad too. Personally, I'd just replace it as it is tooo cheap. $30 or so.
"but no signal is going to monitor"
have you tried another monitor? Testing this monitor on another system? Have you looked at the connector to see if any pins are bent? Is it seating properly?
Sounds like lightening... ;-(