need expert advice on PSU

[katiehlvr1]

Hi,
I need some help with a problem that has now left me with nothing.
I live in FL and the past week we have had some bad storms. The past few days i have noticed these things,
I hibernate my computer. I have an emachine that is about 3-4 years old, runs great with 1 gig ram. A dvd burner and dvdrom
I have been burning alot of movies this week, and two days it was hibernating when i was at work. I came home from work and seen we had lost electric at one point. The green light was on but a black screen. I listened to the back of the PSU and it the fan sounded as if it was going off and on, and a dvd was left in the rom and that was making a strange noise almost as if it was trying to read it.
i could not do anything with the pc but pull the plug. I gave it a good 10 minutes and it started up fine and was on it the remainder of the night ripping.
The next night i did the same thing with ripping, no problems or reboots of any kind. I went to bed and left the pc on while it was ripping another movie. I did not have any loss of electricity that night. I woke up in the am and noticed it had burnt the movie as the rom ejected the disc but once again the green light was on and a black screen. The psu was making a strange sound. THis time it felt as if it was going back and forth with the fan, a little here, silent, a little there. I pulled the plug.
Today when i came home from work we had another loss of electric. The green light was on but total silence.
I tried powering it up and got nothing. I pulled out the psu and smelt the "burn smell" it was very hot as if it had happened a little before i got home from work. i took the cables off the drives, and put em back in and powered it up. The fan kicked on in full force for about 5 secs and then died. I tried putting in an OLD OLD supply but got nothing, so i put mine back in. At this point now, I get the green light on the face of the tower, cannot power up, and there is a ticking noise on the PSU. Could my motherboard be toasted? I do not really know what happens when the cpu goes or motherboard is fried. I just have no clue now. I am really hoping it is the PSU but the one i tried worked in the old machine but did not work on my emachine which makes me nervous about it not being the power supply and there being MUCH worse. It just doesnt make sense as to why when i am on it all night burning away i had no problems, but i leave it to burn and i would come back to this mess the past three days.
Can anyone give me some answers or knowledge about this? Everything is plugged in fine. I just dont know if i should get a new psu or what. If the fan doesnt work and wont power up, would a bad m/b cause this? It is just odd that the PSU has been making these sounds and acting like this over the course of a few days. heavy computer use at night, but if left alone i had come back to a green light and black screen but able to power up, now a green light, black screen and no power up. I know there are different parts of the psu that could cause the green light to be lit but still not be good enough to start the unit. I smelt all around the motherboard and the only smell I got was from the PSU. Also when i was plugging in the ac cable to the pc it was making some electric noises which was bizarre. I tried a new ac plug as well. HELP please.........
the red switch was and is always on the correct setting with the voltz (on back of pc)