Random Power Downs

This has been stumping me as of late, so I figured I'd find somewhere to post for the opinion of somebodies that could help.

To begin with, heres what im running, if you need more details on specific parts, feel free to ask and I'll grab whatever i can.

Approximate computer age: 1 year+
Motherboard: ECS Photon Deluxe 1.1
Harddrive: Maxtor 6L100P0, 100gig
Ram: Currently running an old 256 stick, but, normally: 512 DDR400 from Mushkin
Processor: Pentium 4, 2.8ghz
PSU: Supposably 450watts, although, I speculate it may be 210 (details below)
Video: Nvidia FX Geforce 5500
Sound: Sound Blaster Audigy
Other: Belkin Wireless G network adapter (PCI)

The Problem: While running, either in idle, in games, or just while chatting, the power to the computer will, for lack of a better word, die. It powers off and the only way to get it to power back on is to manually flip the PSU switch it back, wait 5 seconds, reflip, and then power it back on. As noted, it'd done it while in idle, while playing final fantasy XI (thats the current game) and while I'm chatting on aim. What sparked it to start this, i have no idea, its been doing it for about 3-5 days now, nothing was done to the pc in terms of software/hardware changing beforehand.

Solutions I have tried:
~~I checked the my computer > manage and i found nothing wrong with it.
~~I cleaned out the whole case, making sure each of the fans were spotless.
~~I've checked temperature readings. It usually sits at about 40C, doesnt get past 60C while gaming. 40-50 is about average.
~~ Just started checking voltages, I know nothing of it, but, here are the readings according to Motherboard Monitor:
Core 0: 1.49V
Core 1: 1.5V
+3.3: 3.25V
+5.00 5.11V
Again, I dont know much about voltages, so I have no idea what those numbers entirely mean.
~~ Took out the 512 ram stick and left in a 256, to see if it was a memory issue. I tried also running memtest, somebody suggested it, but it came up clean.
~~ Computer has been defragged.

I thought it might have been a power issue. I looked at the PSU hoping to see the voltage and it says "total output: 210W", which i know is damn low for a psu. However, it is supposed to be 450, i ordered it as such. I looked at another model of a PSU from the same manufacter, the stickers resemble each other, but their voltage/wattage is correct.
Thinking it was the issue, I have unplugged the cdr-rom, and I had unplugged 2 of the 3 fans at one point. (I left the case completely open and monitored the temperatures just in case) However, the problem still persisted.

On average, it lasts about 5 or so hours before giving up. Sometimes more, sometimes less, it literally depends on her mood.

Other semi-important information:
It's always been a cranky one to start with, Ive had an issue like this before but it, literally, just went away. I thought i might of had a bad sector of ram, but it doesnt appear to be it.
The computer is about a year old, and its been rarely shut off to an extended length of time, save when im moving it around the house, restarting it, or bringing it home from the form.
When it does power off, theres no warning, no noises really, it just randomly gives up.
Im somewhat of a noob, haha, I had a bit of assistance in figuring out parts, but building it was a total experiment

Im tempted to replace the PSU, because that seems like it may be the issue. My only other guess would be the video card or memory. I dont know much about hardware, so im under the assumption that should it have been anything but the PSU, i would at least get a BSO or it would freeze.

I dont have much of a budget, so Im trying to not have to replace all the parts if i dont have to. As much as I would like to upgrade it, a laptop is more feasible for school. I intend to build a new one in about 2 years, when I know more of what i was doing.

 

Has a friend got a power supply that you could try/ borrow. ?

 

unfortunatly, i dont think so. Most/all of the kids in the dorm hall have a laptop, so I cant test it. It does make a wierd clicky soundish as of late, so Im tempted to just try to replace it. Its been literally running for probably a year or so straight now, so it cant hurt.

Heres what I was tempted to try out:
http://www.newegg.com/Product/Product.asp?Item=N82E16817158008

same manufacturer, if mine is really running at 210 it'll be a big boost. And its cheap enough that it isnt a complete waste if it doesnt work. Im on a tight budget, and as much as I would love to buy a $120 one, i cant. That'll have to wait when i build the "real" one in a year or two.

 

If youn manage a branded one, you get more power, and reliability.
That one was only 350 Watts, Is this one beyond your grange ?

http://www.newegg.com/Product/Product.asp?Item=N82E16817171007

 

I do not know how their mail in discount works

 

nah, i can manage to spend a little extra if it means it'll help fix the situation, id rather throw away a lil extra now than have the thing explode in a month, so to speak

 

350 watts is way more than enough to run your setup IFyou get a decent brand. Try this one: http://www.newegg.com/Product/Product.asp?Item=N82E16817153023

 

my biggest worry is that, if i buy a new psu, will that fix the problem? or is there something else wrong with it.

 

I agree with you, that was why I said, could you borrow one.
You need to do some PC housework first, before spending anything.
To test your memory, you can download a freeware tool from this site, I will get the url for you.If the machine has been knocked ,or, moved, you could check to see if the memory sticks are not making a good contact,- Remember your antistatic drill, and power disconnected- Ease of the clips and remove them, (-if you have a can of compressed air, -make sure system is cold, clean out memory slots) and replace.
A build up of fluff and dust inside the computer could cause no end of startup, and other problems - This would be a good time to clean it out- Mum's old make up brushes, as long as they are old,but, (Kitchen Lady might have one) clean, or, unused, work a treat.- a can of compressed air is a valued tool.
You can do little to clean the power supply, but an air can, might shift some if the mesh, or, fan is dirty.
There is another little tool-- Everest Home - which can tell you if the PC is overheating.--I will find the url for you.

 

BOTH THESE PROGRAMS ARE ABSOLUTELY FREE, AND WILL UPSET YOUR SYSTEM.
EVEREST HAVE A MEMORY BENCHMARK, BUT MEMORY TEST MIGHT HELP IF YOU WANT TO GO FURTHER.
READ THE PAGE FIRST, THEN DOWNLOAD EVERST HOME FREE EDITION
http://www.majorgeeks.com/download4181.html

Read the page on this MEM TEST
BEFORE DOWNLOADING - YOU WILL SEE IT CAN BE ONE POSSIBLE CAUSE
http://majorgeeks.com/MemTest_d350.html