Brand new build shuts itself down after a few seconds of powering up

I have a brand new expensive rig (only thing I cheaped out on was the HD, which I took from an older Gateway. The thing ran like a champ for about 2 weeks, but one morning I pushed the power button and it began to power up (LEDs on, CPU and Case fans turning, Video card fan going, etc), but then shut itself off after about 5 seconds. Since then, the power button on the case does nothing--no start up, or anything.
Oddly enough...when the PSU is unplugged and then plugged back in, or when the PSU switch is flipped off and then on, the computer attempts to power itself up but shuts down (exactly as described above). I spent hours messing with it, and ON ONLY ONE OCCASSION, got the power button to do something (but it still shuts itself down exactly as per all the previous attempts.)
I have attempted the following...
Checked ALL connections, and have connected and reconnected every one.
Reseated the RAM
Taken out a stick of RAM and tried starting with only one (one tech forum was adamant that I attempt this)
Dispersed Internal Voltage (following steps a tech gave me)
Tried started fewer components each time, until it was just the PSU and the motherboard and processor--same result.

The part that really stumps me is that the PSU will attempt to start the computer as soon as it is plugged in WITHOUT ME TOUCHING ANYTHING. MyPSU should be rocking the house (I have an FSP 700w Epsilon) and it is less than 5 months old. All the other computers are spanking new, right out of the box, with the exception of the HD (mentioned above)

 

Hi Realms,

Power supplies have protective circuits for over current, over voltage and under voltage. If any of these occur the PSU shuts down and will not restart until you remove all AC power either by pulling the plug or flipping the switch on the back of the PSU off if present. Your symtom is indicative of an overload on the PSU or a defective PSU. Best troubleshooting at this time is another known good PSU or try yours in another Comp.

Good Luck,Jim

Edit: Since you built it yourself, try removeing loads and see if it runs longer. Start with MB, one stick of Ram and PSU. Add Keyboard and then add loads one at the time. You could also have a defective component drawing too much current.

Jim

 

Double check the seating of the CPU and the heat/sink fan. I had that happen one time with a pc build.
Not sure what the deal was but I pulled out the cpu and re-seated it...everything was fine after that.
Go into bios and find your temps (if it will stay on long enough to do that)

Also... If you could get a hold of another PSU I would try to swapping em out.

If it does the same thing with another psu then you know you can scratch that one off the list.

 

Ok...pulled out everything except CPU, heatsink and fan, and the motherboard....still same results. Switch PSU off and then on, the computer attempts to start itself without pushing power button, but shuts itself down after 4-5 seconds....I took off my upgraded heatsink and fan, reseated CPU, applied new thermal paste, and installed the stock AMD heatsink/fan, with no luck either. Had my buddy reset CMOS jumper or whatever that thing is, no luck either. Bought a brand new Corsair 750w PSU, no luck with that either...

 

Alright, I may have found the problem. When I ordered the CPU from partspc.com, it recommended a heatsink/fan upgrade, a Thermaltake Venus 12, which I sprung for. It seemed to work like a champ until this problem occurred, I checked the temps in the BIOS shortly after installation and it was quite cool. Recently, I was going through all my paperwork for the various parts, so I took a look at the manual for the Venus 12. According to the paperwork, Venus 12 is compatible w/ AMD Opteron and 64, BUT DOES NOT MENTION COMPATIBILITY WITH THE PHENOM QUAD I HAVE BEEN RUNNING. So, I am assuming that the heatsink/fan was not up the job and my processor fried. I packaged up the processor and sent it to AMD for warranty. My next question is, should I send in the ASUS mobo as well? Could the processor overheating (if this is what happened) have damaged the mobo?

 

Another question is...when and if the processor is fixed and my rig gets running again, should I rely on the stock AMD heatsink/fan? It seems kinda weak and chintzy...

 

I have been using the stock fan, albeit on a different processor (Athalon X2 6000+) and it has never given me any problems.