MC1 Switched Power Supply

Switch Mode power supplies usually are left on permanently and as a result the start up circuit is never used. When the power in the house goes off, the start up circuit is not working because the start up capacitor has "dried up" and lost its value. Unfortunately some times it half works and takes the output stage out.
Check for a semiconductor fuse in line with the transformer. It may have failed.
Firstly ensure the main large capacitors have totally discharged otherwise when removing the components, there is a chance that they will damage other components.
The components to look out for are, on the mains side, small electrolytic capacitors that when you measure them with a capacitance bridge, they are low value. The components must be removed to test them.
On the power side of the board, there are a few large capacity capacitors, they usually show physical signs of aging and can be replaced.
Alswo to look for are any very high value resistors. Sony love to use 22Mohm resistors that go open circuit as do other manufacturers.
I hope that gives you an insight into switched mode power supply repair.

Is your question referring to resetting a Power Supply, as you would per se a surge protector?

In most cases No.
Most Power Supply's do not use a Circuit Breaker, nor a Fuse.
(May have to take that statement back, on some of the new Power Supply's though)

Once the Power Supply has gone bad, (Weak Voltage power rail, usually), it's time to buy a new one.

I find that Electrolytic Capacitors have failed, in most failed Power Supply's. However, that is just my general observation over the past 20 years.

Low quality Electrolytic Capacitors are used.
(Radial Aluminum Electrolytic Capacitor's)

These capacitors are used as Filters for the Power Supply. They filter the incoming AC electricity, and the outgoing DC electricity the Power Supply has converted.
(Input Stage, and Output Stage)

To wit:

The Power Supply used in a personal computer is an SMPS.
Switched-Mode Power Supply,

http://en.wikipedia.org/wiki/Switched-mode_power_supply

Here on the above Wikipedia page for SMPS, you will see a photo to the top right, of a typical SMPS.
You can click on the photo to enlarge.
(You can enlarge twice)

You are looking at a top view of a typical SMPS, that has the cover removed.
The large Electrolytic Capacitors, indicated by the letter B, are for the Input Stage.
The smaller Electrolytic Capacitors, indicated by the letter E, are for the Output Stage.

NEVER open a Power Supply, (SMPS), and try to work on it.

Even when a capacitor is removed from power, (Power Supply unplugged from power), the capacitors hold a charge for a LONG time.
Weeks, Months, sometimes over a year!

If your fingers touch the terminals on the bottom of a capacitor, (Radial Aluminum Electrolytic Capacitor), the charge could be released to YOU!

If your fingers complete a circuit that one, or more capacitors are in, the charge could be released to YOU!

The released charge can be a BAD shock to FATAL!

There are also MOSFET's, and Rectifier Bridge's that can go bad in an SMPS.

There is a Proper way to discharge a capacitor. I will not detail it here because of the safety issue to you.
The best method is to replace the Power Supply.

Tell me the computer manufacturer name, and Model Number, and I will look up what Power Supply it uses, if the info is available.
(90 percent of the time it is)

For any questions please post in a Comment.
Regards,
joecoolvette

This could be one of Three different things:

1) Your PC is overheating. Clean out the dust around the processor fan and intake vents. Make sure that your fan is working. Make sure that the North and South Bridge chips are not overheating either (the two other large chips on the motherboard)

2) Your Motherboard has defective Capacitors. Once your Capacitors start bulging or leaking, the board will need to be replaced.

3) Your Power supply is failing. Not dead yet, but enough of a pause in power distribution to cause the entire system to go down. Power supply can be replaced as well.

You likely have some failed electrolytic capacitors in the A/C to D/C power supply, The set detects the voltages produced are incorrect, or there is an overload{likely the backlight CCFL tubes}so the power supply protects itself [and you] from smoking self-destruction.
If you feel technically inclined, you can remove the back panel and do a visual inspection for leaky, bloated or popped capacitors. Replace with low-ESR of the same voltage/capacitance and size.
tom

Bad Power On switch, or bad power supply.
My money's on the bad power supply.

There is a way to bypass the Power On switch. Should you wish to know the procedure, state so in a comment.
(Believe upper right of page)

After you have made sure it isn't a bad Power On switch, check to make sure the 20-pin ATX motherboard power cable, is seated in the motherboard. TIGHT.

(Whitish see-through, long connector on motherboard.
Has 20 socket holes. 10 on each side.

Make sure the power cable is plugged in all the way, to this connector.
Make sure the lock on the side of the connector, is snapped in place.

(This one,

http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain20

REMEMBER, computer unplugged from power! TOUCH the metal frame of the computer case, BEFORE you reach inside the computer.
Relieves your body of Static electricity)

Next, Power Supply.

When you press the Power On button, you are pressing a Momentary Contact switch.
The Power On switch that is behind the Power On button.
The switch is spring loaded inside, so that when you let go of the button, the switch opens up.
No contact.

When the switch makes contact for a brief second, a circuit is created. 5 Volts is sent through the motherboard, to the Power Supply.
The Power Supply turns on.

Power is sent to the motherboard. BIOS is the first program to be turned on.

BIOS 'see's what devices are installed, does a Ram Memory count, turns the Processor on, and hands the computer over to the Operating System.
(Windows XP is an example of an O/S)

Not enough power to turn the Processor on.

Your power supply has a weak voltage power rail, or a failed voltage power rail.

The power supply you have for your MSI K8N Neo Platinum, has three main voltage power rails.
1) The 3.3 Volt rail
2) The 5 Volt rail
3) The 12 Volt rail

Inside the Power Supply.
There are many components used inside a SMPS power supply, (Switched Mode Power Supply)
The main component that fails is an Electrolytic Capacitor, (Or more than one)

(Information about SMPS,

http://en.wikipedia.org/wiki/Switched-mode_power_supply

You can click on the photo to the top right of this page, to enlarge it.
Main thing I'm pointing out here, are the Electrolytic Capacitors.
The large one's on the left side, are used in the Input Stage.
The smaller one's on the right are in the Output Stage.
This IS NOT, an invite to open your Power Supply!! Read the info at the end of this solution)

Electrolytic Capacitors can fail. When they do, you have a failed voltage power rail, or more than one.

ALL the lights used in your computer use less than 1 Watt.
EACH fan uses 2 to 3 Watts.
A typical Processor uses 55 to 125 watts.
Depends on what Processor it is.

[The MSI K8N Neo Platinum motherboard has a Socket 754 processor socket. Uses AMD Athlon 64 processors.

An AMD Athlon 64 processor that fits a Socket 754, can use 51 to 89 Watts.
Again, it depends on which Athlon 64 processor it is)

Solution?
Use another Compatible, Known to be Good, power supply for a test.
When you have conclusive proof that it is a bad power supply, replace it.

NOTE*
As stated, Do Not open your power supply to try to fix the problem.
The Electrolytic Capacitors inside, can hold a charge for Weeks, sometimes Months!

Should your fingers touch the terminals on the bottom of a capacitor, OR, touch a circuit that one or more capacitors are in,
the Charge could be released to YOU!

Shock ranges from BAD to FATAL!

Best method is to use a substitute power supply for a test.
Be Safe.

hello,
a noise may accure in power supply due to a short circuit or fan does not run properly. if you smell like burnt then you should remove the power supply from pc and open it. then check the capaciter and other element and if you find any broken capaciter then change it with it original value.
ramesh

Failing power supply- 
Nearly all modern electronics uses a 'switched mode power supply.'
They are more efficient, also much more prone to failure but offer the added benefit of being designed so a 'downstream' fault will cause the supply to enter a cyclic state to avoid setting fire to your home.
The supply itself will also cycle if it has an internal problem; once again, to prevent destroying itself or anything dependent on its outputs.
 
Supplies built a couple decades ago could only do this by blowing a fuse and there are conditions that can occur that would not blow the fuse but would allow overheating and further damage as well as fire.
 
The most common failure is of electrolytic capacitors which sometimes will show their illness by causing a bulging top or depositing a crystaline trace around their base.
Often though, they show no outer signs of failure but their value can shrink to tenths of a percent of the specified due to poor seals and defective chemicals. These can only be found through measurement with a capacitance meter with a DF (dissipaton factor - loss) capability. 
They will be in size from ~ 3/8" to 2" in height, ~1/4" to 1 1/4" in diameter, cylindrical, perpendicularly mounted on the board.
They will have markings on their shrink-wrapped sleeves (color can be any) and range from ~ .1 to several hundred uFd. with voltages from 3-4 volts to hundreds.
  
Power supplies are often mounted on a separate board (since they are often outsourced) so if you are adventurous, take the back panel off and take a look.  

I have the same problem with the lights. Already replaced the main board and y-sus - didnt seem to fix. any help?

u might just have a overheating prossesor.try cleaning the vents with an airosol spray and either adding a prossesor fan to the vent or setting the xbox infront of a large fan to help cool it .