Power supply fried after installing new video card

[runningfish007]

First off, here's my system:

MSI K8N Neo2 Platinum
AMD 64 3200+ 939-Socket
4x Kingston 512MB DDR-400 PC-3200
Sony DVD 16X
Western Digital 120GB Serial ATA
Radeon X800 XL/Nvidia MX 4000

My case is from compusa and is a generic ATX case with a 400 watt power supply (which was included with the case).

The problem is, I switched out my old video card (Nvidia MX 4000 series) for my new Radeon. I plugged in the power and pushed the power button, but nearly nothing happened. The fan in the ps didnt start. The proc cooling fan spins for about a second then stops, the small fan on the motherboard spins for about the same time and the led light thats built in to the front of my case turns on for about the same amount of time as those other two fans spin. I thought that quite possibly i over drew the power supply so i switched back out the cards so that i had the old configuration. Now that the hardware is back to the way it was i turned the power on and i get the same result. Is this a tell tale sign that my ps is shot. The proc colling fan and led light go on for a sec but the ps fan doesnt move at all. Thanks for any help in advance.

[JANINE]

quite possibily a dead power supply unit or a connection to the motherboard isnt correct.

do you have another psu of which you can try with the components you have listed above?

[runningfish007]

Unfortunately no I don't at the moment. Is it possible that a supposed 420 watt supply doesnt really support 420 watts?

I went here http://www.jscustompcs.com/power_supply/Power_Supply_Calculator.php?cmd=AMD
and calculated my power at 330 watts minimum.

Also the power supply is made by a company called Channel Well. I'm not too techno savvy but ive never heard of this before.

[JANINE]

its possible i suppose but i've not heard anything like that. anythings possible. see if you can get a mate to let u borrow a psu.

for what its worth i havent heard of channel well before.

[runningfish007]

I disconnected everything from the power supply and found something quite interesting. The plastic coating on the power leads to my floppy drive had melted off. Anyways, with everything disconnected, I pluged in just the power to the back of the computer and turned it on and nothing happened.

I'm gonna end up getting a new ps anyways because of the melted wires now.
I'm pretty much set on an antec ps but im not sure how much power to push. I used the calculator and added up all the things im gonna end up with and hit just about 400. I was thinking of getting at least the 480 watts but was wondering if making the extra push to the 550 would be worth it.

[JANINE]

it depends on what you are thinking of adding in the future. if you are thinking of adding extra optical or hard drives then the extra power output would be good. antec are probably one of the best manufacturers of psu's so yeah go for it.

regarding the interesting little problem with the floppy drive connector, be very wary as other power connectors (although they may look ok) may also be frazzled. personally if this had happened to me i would want to ensure that my mainboard still works first as well as my processor.
It sounds as if you actually had a power surge from the mains which in turn blew out the power supply and then the charge travelled down the wires to your floppy drive. you'll need a new floppy drive as well, and maybe a whole load of new components and hardware. sorry but its the brutal truth.